Non-thermofusible phenol resin powder, method for producing the same, thermosetting resin composition, sealing material for semiconductor, and adhesive for semiconductor

ABSTRACT

Disclosed is a non-thermofusible phenol resin powder having an average particle diameter of not more than 20 μm and a single particle ratio of not less than 0.7. This non-thermofusible phenol resin powder preferably has a chlorine content of not more than 500 ppm. This non-thermofusible phenol resin powder is useful as an organic filler for sealing materials for semiconductors and adhesives for semiconductors. The non-thermofusible phenol resin powder is also useful as a precursor of functional carbon materials such as a molecular sieve carbon and a carbon electrode material.

TECHNICAL FIELD

The present invention relates to a non-thermofusible phenol resin powderand a method for producing the same. More specifically, it relates to ahighly safe non-thermofusible phenol resin powder useful as an organicfiller or a precursor of a functional carbon material such as amolecular sieve carbon, a carbon electrode material or the like andsuitably employable as an additive for materials over various industrialfields such as a molding material, a paint, a refractory, papermaking, afriction material, an abrasive and an adhesive and a method forproducing the same. Further, the present invention relates to athermosetting resin composition containing this non-thermofusible phenolresin powder, as well as a sealing material for a semiconductor and anadhesive for a semiconductor employing this thermosetting resincomposition.

BACKGROUND ART

A phenol resin is a material excellent in the balance between heatresistance, dynamical performance and electric characteristics and thecost, and utilized in various industrial fields. In particular,applicability to various fields has recently been found as to a granularor powdery phenol resin or a hardened substance thereof, and someproducts are already put on the market as multiuse materials.

For example, Japanese Patent Laying-Open No. 57-177011 (PatentDocument 1) discloses a granular or powdery phenol resin hardenedsubstance consisting of a condensate of a phenolic compound andformaldehyde, and this is put on the market with a trade name “Bellpearl(registered trademark) Type R” (by Air Water Inc.). This phenol resinhardened substance is useful as an organic filler for supplying heatresistance or improving sliding properties or a filler for reducing thequantity of gas generated when hardening an unhardened phenol resin orthe like, for example. Further, this is a resin having a high residualcarbon ratio due to the chemical structure thereof, and hence the sameis useful also as a firing precursor of activated carbon or a powderycarbon material suitably used as a carbon electrode material, forexample. In addition, the granular or powdery phenol resin hardenedsubstance described in Patent Document 1 contains neither a harmfulphenol monomer nor a low-molecular condensation component, and has highsafety.

When employing the aforementioned phenol resin powder or the hardenedsubstance thereof as an organic filler or a precursor of a powderycarbon material, the shapes and configrations of the particles thereofmust be properly controlled, in order to exhibit desirable performanceas the organic filler or the precursor of a powdery carbon material. Inother words, it is necessary that (i) the average particle diameter ofthe particles is sufficiently small, and (ii) there is hardly anysecondary aggregate resulting from aggregation of primary particles, inorder to attain a high filling property in a product, a high specificsurface area in formation of the powdery carbon material and lowviscosity in a use as an aqueous slurry. In addition to the above (i)and (ii), it is more desirable that (iii) the particle size distributionof the particles is sufficiently narrow, and/or (iv) the shapes of theparticles are closer to a spherical shape. Further, it is desirable that(v) the residue of a phenol monomer (free phenol) in the phenol resinpowder is smaller, in consideration of safety of the product to whichthis phenol resin powder is applied or safety in production. Theaforementioned sufficiently small particle diameter must be at least notmore than 20 μm, more preferably not more than 10 μm, in considerationof application of the phenol resin powder or the hardened substancethereof to various industrial uses.

However, although a large number of studies have been heretoforeconducted as to the phenol resin powder or the hardened substancethereof, it is the present situation that a phenol resin powder havingthe aforementioned characteristics or a hardened substance thereof isnot yet known and a production method suitable for mass production ofsuch a phenol resin powder or a hardened substance thereof is not yetknown either.

For example, while the aforementioned Patent Document 1 describes atechnique of obtaining a granular or powdery non-thermofusible phenolresin by optimizing synthetic conditions such as the ratios ofquantities of formaldehyde, phenol, hydrochloric acid and a water mediumas used and a temperature condition, the obtained non-thermofusiblephenol resin had such points to he improved that (i) the primaryparticle diameters are relatively large, (ii) the quantity of secondaryaggregates formed by aggregation of the primary particles is relativelylarge, (iii) the particle size distribution is wide, and (iv) the resincontains a large quantity of particles having shapes other than aspherical shape.

Japanese Patent Laying-Open No. 2000-239335 (Patent Document 2)discloses a spherical phenol resin hardened substance obtained byreacting phenol and formaldehyde with an alkaline catalyst in thepresence of a suspending agent and thereafter performing hardeningreaction with an acidic catalyst. However, the average particle diameterspecifically described in Example is 100 to 800 p.m.

Japanese Patent Laying-Open No. 50-98537 (Patent Document 3) describes atechnique of obtaining a non-thermofusible phenol resin powder by addinga cellulosic compound to an initial condensate obtained by reacting aphenolic compound and a formaldehyde in the presence of at least one ofan acidic catalyst and a basic catalyst and a nitrogen-containingcompound, granulating the mixture by further continuing the reaction andthereafter performing dehydration/drying. However, the average particlediameter of this phenol resin powder is about 700 μm. Further, thephenol resin powder contains about 6000 ppm of free phenol, and there isroom for improvement in view of safety.

Japanese Patent Laying-Open No. 2001-114852 (Patent Document 4)describes a technique of obtaining a spherical phenol resin bycondensing a phenolic compound and an aldehyde in the presence of acondensation catalyst and an emulsion dispersant under conditions of atemperature of at least 105° C. and not more than 200° C. and a pressureof at least 1.3 kg/cm² and not more than 15 kg/cm². This sphericalphenol resin has an average particle diameter of 2 to about 200 μm, asdescribed in Example. However, the technique is accompanied with suchcomplicatedness that the reaction is performed with an autoclave, andthere has been such a problem that the particle diameter remarkablyfluctuates depending on a stirring method or a rate of stirring.Further, the reaction pattern is essentially similar to that in theaforementioned Patent Document 3, and the chemical structure of theobtained phenol resin is also conceivably equivalent, and hence thephenol resin conceivably contains a large quantity of free phenol.

Japanese Patent Laying-Open No. 59-6208 (Patent Document 5) describes aspherical phenol resin obtained by hardening a dispersion of aresol-type spherical phenol resin, obtained by reacting a phenoliccompound and a formaldehyde with a nitrogen-containing compound catalystin the presence of a water-soluble polymer compound, with an acidiccatalyst. However, the spherical phenol resin obtained by this methodhas a large average particle diameter of about 350 to 520 μm.

Japanese Patent Laying-Open No. 2002-226534 (Patent Document 6)discloses a method for producing spherical resin particulates fromresorcin and an aldehyde by setting the ratio (weight ratio) of theresorcin and water to 1:5 to 1:100 and adjusting the pH of the reactionsystem to 5 to 7. These spherical resin particulates have an averageparticle diameter of 500 nm to 2 μm, as described in Example. However,there is such a problem that only the resorcin can be used as the phenolsource, and hence the residual carbon ratio of the obtained phenol resinis conceivably low as compared with a case of employing another phenoliccompound such as phenol.

Japanese Patent Laying-Open No. 10-338728 (Patent Document 7) describesa method for producing a spherical phenol resin hardened substance byremoving a solvent from a homogeneous mixed liquid containing a phenolresin, a cellulose derivative and the solvent, causing phase separationof the phenol resin and the cellulose derivative, hardening the phenolresin and thereafter removing the cellulose derivative from thecomposite of the phenol resin hardened substance and the cellulosederivative. A spherical phenol resin hardened substance having anaverage particle diameter of 28 nm to 5 μm is obtained by this method.However, an organic solvent problematic to the environment and safety ofthe human body must be used in this method. Further, the phaseseparation reaction in a solid phase is utilized, and hence a long timeof 21 hours to 114 hours is required for formation/extraction of theparticles. Japanese Patent Laying-Open No. 7-18043 (Patent Document 8)discloses a method for producing a spherical phenol-formaldehyde-basedresin by reacting a phenol compound and formaldehyde in a specificquantity of water or a mixed solvent of water/water-compatible organicsolvent in the presence of an acidic catalyst while condensing thesolvent and hardening deposited novolac spherical particles by reactionwith a hardening agent. According to this method, a spherical phenolresin having a particle diameter of about 9 μm or 15 μm can be obtained,for example. However, it cannot be said that the spherical phenol resinobtained by this method is sufficiently satisfactory in the point of theparticle size distribution. Further, the reaction pattern is essentiallysimilar to that in the aforementioned Patent Document 3, and thechemical structure of the obtained phenol resin is also conceivablyequivalent, and hence the phenol resin conceivably contains a largequantity of free phenol.

Although various methods such as that employing an additive such as asuspending agent or an emulsion dispersant and that optimizingpolymerization conditions etc. for the phenol resin have generally beenproposed as techniques for obtaining particulates of phenol resins,phenol resin particles having a minute average particle diameter of notmore than 20 μm, preferably not more than 10 μm, hardly containingsecondary aggregates, having an extremely small content of a monomerphenolic compound and having high safety and a method for producing thesame have not been proposed. Further, such a phenol resin powder thatthe shapes of the particles thereof are spherical and the particle sizedistribution of the particles is sufficiently narrow in addition tothese characteristics and a method for producing the same are notproposed.

For example, even if the polymerization conditions etc. for the phenolresin are optimized, it follows that the obtained phenol resin containsa monomer phenolic compound in a high content substantially identicallyto the prior art when the polymerization conditions for polymerizing thephenolic compound and the aldehyde themselves are essentially equivalentto the polymerization conditions having been employed in general. Insuch a method for producing a phenol resin powder that a rate ofstirring influences the particle size, the particle size distributioninevitably widens since the inner portion of a reaction vessel cannot becontinuously homogeneously stirred.

An integrated circuit device such as an 1C (Integrated Circuit) or amemory generally consists of a semiconductor element, an insulatingsupport substrate, a lead frame and a lead, and a sealing material or anadhesive is employed for sealing and bonding these. In general, it hasbeen a mainstream tendency to employ a resin composition containing aninorganic filler such as spherical silica, epoxy resin and a hardeningagent for such a sealing material or an adhesive.

In recent years, however, heat resistance has been required to a sealingmaterial and an adhesive, in order to cope with increase of a solderingtemperature resulting from transition to lead-free solder andapplication to an electronic component such as an on-vehicle electroniccomponent requiring a high-temperature operation assurance. Further,while refinement of the filler in the sealing material and the adhesiveand reduction in viscosity of the sealing material and the adhesive arerequired in order to cope with further refinement of internal wires ofthe integrated circuit chip, it has been difficult to satisfy these bothnew required characteristics with conventional blending.

In other words, epoxy resin which is an organic substance and sphericalsilica (fused silica) which is an inorganic substance are remarkablydifferent in linear expansion coefficient from each other, and hencesuch deterioration comes into question that stress is formed on theinterface between the epoxy resin and the spherical silica to causecracks in production through a soldering step or the like or followingtemperature rise/temperature reduction in use.

Japanese Patent Laying-Open No. 11-172077 (Patent Document 9) describesa technique of blending an amino-based silane coupling agent acting on asilica surface to a composition for sealing a semiconductor in order toimprove mechanical characteristics of a hardened substance. However,heat resistance of the silane coupling agent itself is low, and henceheat resistance of the sealing material is also relatively low dependingon the heat resistance of the silane coupling agent.

As a means for canceling stress formation on the interface between theaforementioned epoxy resin and the spherical silica, an organic fillerwhich is an organic substance may conceivably be employed in place ofthe inorganic filler such as the spherical silica. This is because thedifference between the linear expansion coefficients of the filler andthe epoxy resin is reduced due to the employment of the organic filler.For example, Japanese Patent Laying-Open No. 2000-269247 (PatentDocument 10), Japanese Patent Laying-Open No. 2002-226824 (PatentDocument 11) and Japanese Patent Laying-Open No. 2004-168848 (PatentDocument 12) describe that an organic filler can be employed for asealing material for a semiconductor or an adhesive for a semiconductor.However, there is no proposal as to a specific organic filler having theaforementioned required characteristics.

The phenol resin is a material excellent in heat resistance, dynamicalperformance and electric characteristics, and utilized as variousindustrial materials such as that for an electronic material. If ahardened substance of the phenol resin can be employed as an organicfiller, the excellent characteristics belonging to this phenol resin canbe supplied to the sealing material or the adhesive for a semiconductor.

However, there has heretofore been proposed no phenol resin hardenedsubstance having high heat resistance and implementing refinement ofresin particles and reduction in viscosity in a case of forming asealing material or an adhesive. Further, while it is desired that anionic impurity content, particularly a halogen ion content is small asthe organic filler employed for the sealing material for a semiconductoror the adhesive for a semiconductor, the phenol resin is in the firstplace ordinarily polymerized in an aqueous medium with an ioniccatalyst, and hence it has been difficult to obtain such a phenol resinhardened substance that the ionic impurity content is reduced to adegree applicable to a semiconductor use.

Japanese Patent Laying-Open No. 10-60068 (Patent Document 13) andJapanese Patent Laying-Open No. 2-245011 (Patent Document 14) describephenol resins in which the contents of ionic impurities are reduced byspecific washing treatments, and mention that these phenol resins areuseful for application to sealing materials for semiconductors or thelike. However, the phenol resins described in these documents areunhardened, and not employed as organic fillers. Further, the washingmethods described in these documents cannot be employed for removal ofan ionic impurity from a phenol resin hardened substance.

-   Patent Document 1: Japanese Patent Laying-Open No. 57-177011-   Patent Document 2: Japanese Patent Laying-Open No. 2000-239335-   Patent Document 3: Japanese Patent Laying-Open No. 50-98537-   Patent Document 4: Japanese Patent Laying-Open No. 2001-114852-   Patent Document 5: Japanese Patent Laying-Open No. 59-6208-   Patent Document 6: Japanese Patent Laying-Open No. 2002-226534-   Patent Document 7: Japanese Patent Laying-Open No. 10-338728-   Patent Document 8: Japanese Patent Laying-Open No. 7-18043-   Patent Document 9: Japanese Patent Laying-Open No. 11-172077-   Patent Document 10: Japanese Patent Laying-Open No. 2000-269247-   Patent Document 11: Japanese Patent Laying-Open No. 2002-226824-   Patent Document 12: Japanese Patent Laying-Open No. 2004-168848-   Patent Document 13: Japanese Patent Laying-Open No. 10-60068-   Patent Document 14: Japanese Patent Laying-Open No. 2-245011

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The present invention has been proposed in consideration of such asituation, and an object thereof is to provide a non-thermofusiblephenol resin powder having a minute average particle diameter,containing no secondary aggregates, consisting of particles having aspherical shape, having a narrow particle size distribution, having asmall free phenol content and having high safety and a method forproducing the same.

Another object of the present invention is to provide anon-thermofusible phenol resin powder having high heat resistance,having a minute average particle diameter, capable of implementingreduction in viscosity when forming a sealing material or an adhesiveand having a reduced ionic impurity content and a method for producingthe same.

Still another object of the present invention is to provide a resincomposition containing a non-thermofusible phenol resin powder havinghigh heat resistance and low viscosity and having a reduced ionicimpurity content, as well as a sealing material for a semiconductor andan adhesive for a semiconductor employing this resin composition.

Means for Solving the Problems

As a result of deep studies, the inventors have found that anon-thermofusible phenol resin powder having the aforementionedexcellent characteristics can be obtained by reacting an aldehyde and aphenolic compound in an aqueous medium with an acidic catalyst of a highconcentration in the presence of a protective colloidal agent andthereafter heating the reaction liquid.

The inventors have also found that it is necessary that the averageparticle diameter of the phenol resin powder is sufficiently small andthe content of secondary aggregates resulting from aggregation ofparticles is small in order to implement reduction in viscosity in aphenol resin composition containing the phenol resin powder, and that ahardened phenol resin powder may be washed with an alcohol and/or analkaline solution in order to reduce the content of an ionic impurity,particularly halogen ions in the hardened phenol resin powder. In otherwords, the present invention is as follows:

The non-thermofusible phenol resin powder according to the presentinvention has an average particle diameter of not more than 20 μm and asingle particle ratio of at least 0.7. The average particle diameter ispreferably not more than 10 μm. Definitions of the terms“non-thermofusible”, “average particle diameter” and “single particleratio” are described later.

In the non-thermofusible phenol resin powder according to the presentinvention, the coefficient of variation of a particle size distributionexpressed in the following formula [1] is preferably not more than 0.65:

coefficient of variation of particle size distribution=(d _(84%) −d_(16%))/(2×average particle diameter)  [1]

where d_(84%) and d_(16%) represent particle sizes exhibiting cumulativefrequencies of 84% and 16% in a frequency distribution obtained by laserdiffraction scattering respectively.

In the non-thermofusible phenol resin powder according to the presentinvention, the sphericity of the particles is preferably at least 0.5.

In the non-thermofusible phenol resin powder according the presentinvention, further, the free phenol content is preferably not more than500 ppm. Definitions of the aforementioned terms “sphericity” and “freephenol content” are described later. More preferably, the averageparticle diameter is not more than 10 μm, the coefficient of variationof the particle size distribution expressed in the above formula [1] isnot more than 0.65, the sphericity is at least 0.5, and the free phenolcontent is not more than 500 ppm in the non-thermofusible phenol resinpowder according to the present invention.

In the non-thermofusible phenol resin powder according to the presentinvention, a chlorine content is preferably not more than 500 ppm, morepreferably not more than 100 ppm.

The present invention provides a method for producing anon-thermofusible phenol resin powder, including (1) a phenol resinpowder forming step of forming a phenol resin powder by reacting analdehyde and a phenolic compound in an aqueous medium in the presence ofan acidic catalyst having a molar concentration of at least 2.0 mol/L ina reaction liquid and a protective colloidal agent, (2) anon-thermofusibilizing step of forming a non-thermofusible phenol resinpowder by heating the reaction liquid containing the phenyl resinpowder, and (3) a separating-washing step of separating thenon-thermofusible phenol resin powder from the reaction liquid andwashing the same. This method is suitably applied as a method forproducing the aforementioned non-thermofusible phenol resin powderaccording to the present invention.

Preferably, the aforementioned acidic catalyst is hydrochloric acid, andthe aforementioned aldehyde is formaldehyde, paraformaldehyde or amixture of these.

Preferably, the feed molar ratio of the aforementioned phenolic compoundwith respect to the aforementioned aldehyde is not more than 0.9.Preferably, the aforementioned protective colloidal agent is awater-soluble polysaccharide derivative.

The separating-washing step may include a step of washing the saidnon-thermofusible phenol resin powder with at least one liquid mediumselected from an alcohol and an alkaline solution. Thus, anon-thermofusible phenol resin powder having a chlorine content of notmore than 500 ppm can be obtained.

Preferably, washing with the alcohol is performed at a temperatureexceeding the glass transition temperature of the aforementionednon-thermofusible phenol resin powder.

Further, the present invention provides a thermosetting resincomposition containing the inventive non-thermofusible phenol resinpowder whose chlorine content is not more than 500 ppm, epoxy resin anda hardening agent. The thermosetting resin composition according to thepresent invention may further contain an inorganic filler.

In addition, the present invention provides a sealing material for asemiconductor and an adhesive for a semiconductor consisting of theaforementioned thermosetting resin composition.

Effects of the Invention

According to the present invention, a non-thermofusible phenol resinpowder having extremely minute particle diameters with an averageparticle diameter of not more than 20 μm and hardly containing secondaryaggregates resulting from aggregation of these minute primary particles,i.e., having a high single particle ratio. Such a non-thermofusiblephenol resin powder according to the present invention can be suitablyemployed as an additive for materials over various industrial fieldssuch as a molding material, a paint, a refractory, papermaking, afriction material, an abrasive and an adhesive, particularly as anorganic filler, or a precursor of a functional carbon material such as acarbon electrode material, activated carbon or a molecular sieve carbon.

According to the present invention, further, a non-thermofusible phenolresin powder having extremely minute particle diameters with an averageparticle diameter of not more than 20 μm, hardly containing secondaryaggregates resulting from aggregation of these minute primary particles,and having a remarkably reduced chlorine ion content is provided. Such anon-thermofusible phenol resin powder according to the present inventioncan also be suitably used as an additive for materials over variousindustrial fields. In particular, a thermosetting resin compositionemploying this non-thermofusible phenol resin powder as an organicfiller is extremely useful as a sealing material for a semiconductor andan adhesive for a semiconductor.

Further, the present invention provides a production method suitable forproducing a non-thermofusible phenol resin powder having theaforementioned excellent characteristics. According to the inventivemethod for producing a non-thermofiisible phenol resin powder, anon-thermofusible phenol resin powder having excellent characteristicscan be produced with a relatively simple method, and the methodaccording to the present invention is a method suitable for massproduction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an SEM photograph of a preferred example of anon-thermofusible phenol resin powder according to the presentinvention.

FIG. 2 is an optical micrograph of a non-thermofusible phenol resinpowder obtained in Example 2.

FIG. 3 is an optical micrograph of a non-thermofusible phenol resinpowder obtained in Example 3.

FIG. 4 is an optical micrograph of a phenol resin powder obtained inComparative Example 1.

FIG. 5 is a graph showing the relation between the concentration of aprotective colloidal agent (weight (ppm) of the protective colloidalagent with respect to the total weight of a reaction liquid) and theaverage particle diameter of a phenol resin powder.

FIG. 6 is a scanning electron micrograph (SEM photograph) (500magnifications) of a phenol resin powder 12A-c obtained in Example 12.

FIG. 7 is a further enlarged SEM photograph (3500 magnifications) of thephenol resin powder 12A-c.

FIG. 8 is an SEM photograph of a preferred example of a carbon electrodematerial powder according to the present invention.

FIG. 9 is an optical micrograph of a carbon electrode material powderobtained in Reference Example 9.

FIG. 10 is an optical micrograph of a carbon electrode material powderobtained in Reference Example 11.

FIG. 11 is an optical micrograph of a carbon electrode material powderobtained in Reference Comparative Example 1.

FIG. 12 is a graph showing the relation between the concentration of aprotective colloidal agent (weight (ppm) of the protective colloidalagent with respect to the total weight of a reaction liquid) and theaverage particle diameter of a carbon electrode material powder.

FIG. 13 is a schematic sectional view showing an electric double layercapacitor produced by way of trial in Reference Example 15.

FIG. 14 is a schematic model diagram showing a preferred example of aPSA nitrogen generator according to the present invention.

FIG. 15 is an SEM photograph of the surface of a molecular sieve carbonobtained in Reference Example 18.

FIG. 16 is a schematic model diagram showing an apparatus for measuringadsorptivity of a molecular sieve carbon.

FIG. 17 is a diagram showing the relation between purity of productnitrogen and a flow rate of product nitrogen gas in a PSA nitrogengenerator employing molecular sieve carbons having different yields.

DESCRIPTION OF THE REFERENCE SIGNS

101 a, 101 b adsorption tower, 102 compressor, 103 air dryer, 104product tank, 105, 106 a, 106 b, 109 a, 109 b, 113 a, 113 b, 115 a, 115b, 116, 305 electromagnetic valve, 107 a, 107 b, 108 a, 108 b, 110, 112,114, 117, 317 pipe, 111 pressure regulator, 301 vacuum pump, 302, 303,308, 316 valve, 304, 307 pressure indicator, 306 constant pressurevalve, 309 gas regulator, 310 gas cylinder, 311 measurement chamber, 312sample chamber, 313, 314 pressure sensor, 315 recorder, 601 slurriedcarbon electrode material, 602 collector, 603 separator, 604 spacer, 605terminal plate.

BEST MODES FOR CARRYING OUT THE INVENTION <Non-Thermofusible PhenolResin Powder>

The non-thermofusible phenol resin powder according to the presentinvention is a non-thermofusible phenol resin consisting of a reactionproduct of a phenolic compound and an aldehyde, and characterized inthat the average particle diameter of particles (also referred to asprimary particles as a term with respect to secondary aggregates) is notmore than 20 μm and a single particle ratio serving as an index as tothe content of the secondary aggregates is at least 0.7. Thus, theaverage particle diameter of the phenol resin particles is set to notmore than 20 μm, preferably not more than 10 μm, and the single particleratio is set to at least 0.7, whereby the phenol resin powder can befilled with a higher filling factor when employed as an organic filler,and a filled substance such as a resin composition filled with thisphenol resin powder has lower viscosity as compared with the prior art,and hence the same is easy to handle. Such reduction in viscosity of theresin composition satisfies prescribed properties of a sealing materialor an adhesive recently required in the semiconductor field.

The phenol resin powder according to the present invention can besuitably employed also as a precursor of a functional carbon materialsuch as activated carbon, a carbon electrode material or a molecularsieve carbon, for example. The average particle diameter of the phenolresin particles is set to not more than 20 μm, preferably not more than10 μm, and the single particle ratio is set to at least 0.7, whereby aspatial filling property of carbon powder obtained by firing isremarkably improved. Therefore, performance of the functional carbonmaterial per unit volume or the surface area per unit weight can beremarkably improved by employing the phenol resin powder according tothe present invention. Further, a dispersion liquid prepared bydispersing the functional carbon material obtained from the phenol resinpowder according to the present invention in a liquid medium such aswater, for example, has such a characteristic that the same exhibits lowviscosity also in a high-concentration region. The dispersion liquidhaving such a characteristic can be suitably employed when preparing acoated carbon electrode, for example. Such a non-thermofusible phenolresin powder according to the present invention can be applied not onlyto the aforementioned use but also over wide industrial fields of amolding material, a paint, a refractory, papermaking, a frictionmaterial, an abrasive and an adhesive.

While a method of pulverizing a hardened phenol resin can be listed as aconventional method for obtaining fine powder of a non-thermofusiblephenol resin, the shape is so indeterminate that no granular substancehaving an excellent filling property can be obtained in this method.

FIG. 1 shows a scanning electron micrograph (hereinafter referred to asan SEM photograph) of a preferred example of the non-thermofusiblephenol resin powder according to the present invention. As shown in FIG.1, the non-thermofusible phenol resin powder according to the presentinvention is a phenol resin powder having minute particle diameters, andthe quantity of secondary aggregates resulting from aggregation of theseparticles (primary particles) is small. The phenol resin powder shown inFIG. 1 is such a phenol resin powder that the average particle diameterdefined below is 5 μm and the single particle ratio is 1.0.

The non-thermofusible phenol resin powder according to the presentinvention is described in detail. The non-thermofusible phenol resinpowder according to the present invention is a non-thermofusible phenolresin consisting of a reaction product of a phenolic compound and analdehyde. The reaction product of a phenolic compound and an aldehydebasically means a product obtained by addition reaction and condensationreaction of these. The reaction product may partially include a productobtained by addition reaction of a phenolic compound and an aldehyde.While the phenolic compound is not particularly restricted, phenol,naphthol, hydroquinone, resorcin, xylenol and pyrrogallol can be listed,for example. The phenolic compound may be one type, or at least twotypes may be combined and employed. In particular, the phenolic compoundis preferably phenol, in consideration of the balance between theperformance of the obtained phenol resin and the cost.

While the aldehyde is not particularly restricted, formaldehyde,paraformaldehyde, glyoxal and benzaldehyde can be listed, for example.The aldehyde may be one type, or at least two types may be combined andemployed. In particular, the aldehyde is preferably formaldehyde,paraformaldehyde or a mixture of these.

In this specification, “non-thermofusible” means that the phenol resinpowder is not welded under a specific high-temperature pressurizingcondition, and more specifically, the term is defined as such a propertythat the phenol resin powder does not form a flat plate, the phenolresin particles are not deformed, or the phenol resin particles do notadhere to each other by fusion and/or welding when about 5 g of a phenolresin powder sample is inserted between two stainless plates of 0.2 mmin thickness and pressed with a pressing machine previously heated to100° C. with a total load of 50 kg for two minutes. Such a property canbe supplied in production of the phenol resin powder by synthesizing thephenol resin by reaction of a phenolic compound and an aldehyde andthereafter crosslinking and hardening this phenol resin. Crosslinkingand hardening can be performed by heating a reaction liquid performingthe reaction of the phenolic compound and the aldehyde, for example.

Boiling methanol solubility of the non-thermofusible phenol resin powderaccording to the present invention is preferably less than 30%, morepreferably less than 20%. In this specification, “boiling methanolsolubility” denotes the content of a boiling methanol soluble componentin the phenol resin powder, and more specifically, the term is definedas a value calculated by the following test: In other words, about 10 gof a phenol resin sample is precisely weighed, heated in about 500 mL ofsubstantially anhydrous methanol under reflux for 30 minutes, thereafterfiltrated through a glass filter of No. 3, and the residue on the glassfilter is further washed with about 100 mL of anhydrous methanol. Then,the washed residue on the glass filter is dried at 40° C. for fivehours, and this residue is thereafter precisely weighed. A valuecalculated through the following formula [2] is regarded as the “boilingmethanol solubility”:

boiling methanol solubility (weight %)=(difference between weight ofphenol resin sample and weight of dried residue)/(weight of phenol resinsample)×100  [2]

The “boiling methanol solubility”, which is not a direct criterion as towhether or not this phenol resin has “non-thermofusibility”, can be oneindex for learning the degree of thermofusibility of the phenol resin.In other words, the thermofusibility tends to be reduced as the “boilingmethanol solubility” is reduced. If the boiling methanol solubility isequal to or exceeds 30%, the phenol resin may exhibit thermofusibilitydue to heating or pressurization in use, and the particles may bedeformed or welded.

The average particle diameter of the particles (primary particles)constituting the non-thermofusible phenol resin powder according to thepresent invention is not more than 20 μm, preferably not more than 10μm, as hereinabove described. The average particle diameter is so set tonot more than 10 μm that a filling property and low viscosity inapplication of the phenol resin powder according to the presentinvention to an organic filler or a functional carbon material and lowviscosity in application to a dispersion liquid can be further improved.In this specification, “average particle diameter” denotes a value of acumulative frequency of 50% in a frequency distribution obtained by ameasuring method employing a laser diffraction particle size measuringapparatus, i.e., laser diffraction scattering (Microtrac method). As thelaser diffraction particle size measuring apparatus, Microtrac X100 byNikkiso Co., Ltd. can be suitably employed.

If the average particle diameter of the non-thermofusible phenol resinparticles exceeds 20 μm, the chlorine content may not be sufficientlyreduced by a method for producing a non-thermofusible phenol resinpowder according to the present invention described later. Also in thissense, the average particle diameter of the non-thermofusible phenolresin particles is preferably set to not more than 20 μm, morepreferably set to not more than 10 μm.

The single particle ratio of the non-thermofusible phenol resin powderaccording to the present invention is at least 0.7, preferably at least0.8. If the single particle ratio is less than 0.7, a filling propertyand low viscosity in application to an organic filler for a sealingmaterial for a semiconductor or an adhesive for a semiconductor or afunctional carbon material and low viscosity in application to adispersion liquid tend to be insufficient. In this specification,“single particles” denote primary particles not forming secondaryaggregates resulting from aggregation, and “single particle ratio”denotes a ratio in a case of dispersing the phenol resin powder in waterdroplets, making optical microscope observation and counting the totalnumber of primary particles and the number of single particles in arandomly selected visual field containing about 300 primary particles,i.e., the number of single particles/the total number of primaryparticles.

The non-thermofusible phenol resin powder according to the presentinvention preferably has a narrow particle size distribution. Morespecifically, the coefficient of variation of the particle sizedistribution of the particles (primary particles) constituting thenon-thermofusible phenol resin powder according to the present inventionis preferably not more than 0.65. The coefficient of variation of theparticle size distribution is more preferably not more than 0.6. In thisspecification, the “coefficient of variation of the particle sizedistribution” is a value calculated through the following formula [1]:

coefficient of variation of particle size distribution=(d _(84%) −d_(16%))/(2×average particle diameter)  [1]

In the above formula [1], d_(84%) and d_(16%) represent particle sizesexhibiting cumulative frequencies of 84% and 16% in a frequencydistribution obtained by laser diffraction scattering respectively, andthe average particle diameter is the average particle diameter definedin the above. The coefficient of variation of the particle sizedistribution is so set to not more than 0.65 that a filling property andlow viscosity in employment as an organic filler for a sealing materialfor a semiconductor or an adhesive for a semiconductor or a spatialfilling property in application to a functional carbon material, forexample, can be further improved, while a phenol resin powder applicableover wide industrial fields of a molding material, a paint, arefractory, papermaking, a friction material, an abrasive and anadhesive is provided. As the laser diffraction particle size measuringapparatus, Microtrac X100 by Nikkiso Co., Ltd. can be suitably employed.

In order to improve the performance of the sealing material for asemiconductor or the like, it is preferable the filling factor of afiller filled in binder resin is improved. As a method for improving thefilling factor of a spherical filler, a method of blending fillershaving different particle sizes can be listed. In other words, this is amethod of performing blending/designing so that a smaller filler justenters between closest packing clearances of a larger filler. Whilefused silica is generally employed for a filler for a sealing material,for example, fused silica materials having different average particlediameters are mixed and used in order to improve the filling factor. Inapplication of such a technique, a filler having a desired averageparticle diameter and having a narrow particle size distribution isrequired. According to the present invention, an organic filler for asealing material for a semiconductor also applicable to suchblending/designing can be provided. Further, in a specific field of anadhesive or the like employed for bonding an 1C chip to a substrate, forexample, there exists such a field that merely the presence of a verysmall quantity of a filler having a large particle diameter (i.e.,having a wide particle size distribution) exerts bad influence on thethickness of a bonding layer to cause difficulty in use even if theaverage particle diameter is small. According to the present invention,a non-thermofusible phenol resin powder suitably applicable also in sucha field can be provided.

The particle shape of the non-thermofusible phenol resin powderaccording to the present invention is preferably as close to a sphericalshape as possible. More specifically, the sphericity is preferably atleast 0.5, more preferably at least 0.7, particularly preferably atleast 0.9. As the particle shape is closer to the spherical shape, i.e.,as the sphericity is closer to 1.0, the filling property and the lowviscosity in employment as the organic filler for a sealing material fora semiconductor or an adhesive for a semiconductor and the spatialfilling property in application to the functional carbon material, forexample, can be further improved, while a phenol resin powder applicableover wide industrial fields of a molding material, a paint, arefractory, papermaking, a friction material, an abrasive and anadhesive is provided. In this specification, “sphericity” denotes, in acase of randomly deciding a visual field containing about 300 primaryparticles in optical microscope observation, selecting 10 primaryparticles having the lowest aspect ratios (i.e., ratios of minoraxes/major axes) and measuring the aspect ratios in projected profilesthereof as to the respective ones of these 10 primary particles, theaverage of these 10 aspect ratios.

The free phenol content in the non-thermofusible phenol resin powderaccording to the present invention is preferably not more than 500 ppm.This free phenol content is more preferably not more than 300 ppm,further preferably not more than 200 ppm.

The free phenol content is so set to not more than 500 ppm that safetyin handling of the phenol resin and safety of products in a case ofapplying this phenol resin to various products can be improved. In thisspecification, the “free phenol content” is defined as a valuecalculated by the following test: In other words, about 10 g of a phenolresin sample is precisely weighed, extracted in 190 mL of methanol underreflux for 30 minutes, and filtrated through a glass filter. Thephenolic compound concentration in the filtrate is determined by liquidchromatography, and the weight of the phenolic compound in the filtrateis calculated. The ratio between the weight of this phenolic compoundand the weight of the sample, i.e., the weight of the phenoliccompound/the weight of the phenol resin sample is regarded as the “freephenol content”.

Further, the chlorine content in the non-thermofusible phenol resinpowder according to the present invention is preferably not more than500 ppm. In the semiconductor field, halogen-free electronic material isrequired in view of safety with respect to the environment and healthand in view of improvement of electronic characteristics and improvementof thin wire corrosiveness, and the chlorine content is preferablylower. If the chlorine content exceeds 500 ppm, the dielectric constantof a resin composition containing the non-thermofusible phenol resinpowder is influenced, a lead wire or the like is easily corroded, andthe non-thermofusible phenol resin powder does not satisfycharacteristics required as a sealing material for a semiconductor or anadhesive for a semiconductor. The chlorine content is preferably notmore than 100 ppm, and the non-thermofusible phenol resin powder can bemore suitably employed for a sealing material for a semiconductor or anadhesive for a semiconductor with such a content. In this specification,the “chlorine content” is a chlorine content calculated by the followingmeasuring method:

Measuring Apparatus: Fluorescent X-Ray Analyzer ZSX100E by RigakuCorporation

Measuring Method: A measurement sample (non-thermofusible phenol resinparticles) and binder powder for measurement are pressurized to form apellet for measurement, and fluorescent X-ray analysis is thereafterperformed in an EZ scan mode with the aforementioned measuringapparatus. A diffraction strength measured value of a chlorine Kα ray isstandardized from an estimated molecular formula (C₇H₆O₁) of a phenolresin hardened substance, and regarded as the chlorine content (wt/wt).While not only chlorine ions but also chlorine atoms of an organicchlorine compound or the like are included in the object of fluorescentX-ray measurement, no organic chlorine compound is intentionally addedwhen the non-thermofusible phenol resin is produced by a methodaccording to the present invention described later, for example, andhence it can be said that the chlorine content obtained by thefluorescent X-ray measurement is substantially equal to the chlorine ioncontent.

While the method for producing the non-thermofusible phenol resin powderhaving the aforementioned excellent characteristics is not particularlyrestricted, the following method can be suitably used. The followingmethod for producing a non-thermofusible phenol resin powder is alsoincluded in the present invention.

<Method for Producing Non-Thermofusible Phenol Resin Powder>

The method for producing a non-thermofusible phenol resin powderaccording to the present invention preferably includes the followingsteps (1) to (3). The respective steps are now described in detail.

(1) A phenol resin powder forming step of forming a phenol resin powderby reacting an aldehyde and a phenolic compound in an aqueous medium inthe presence of an acidic catalyst having a molar concentration of atleast 2.0 mol/L in a reaction liquid and a protective colloidal agent,

(2) a non-thermofusibilizing step of forming a non-thermofusible phenolresin powder by heating the reaction liquid containing theaforementioned phenol resin powder, and

(3) a separating-washing step of separating the aforementionednon-thermofusible phenol resin powder from the reaction liquid andwashing the same.

(1) Phenol Resin Powder Forming Step

In this step, the phenol resin powder is formed by reacting the aldehydeand the phenolic compound in the aqueous medium in the presence of theacidic catalyst and the protective colloidal agent. While the aldehydeis not particularly restricted, formaldehyde, paraformaldehyde, glyoxaland benzaldehyde can be listed, for example. The aldehyde may be onetype, or at least two types may be combined and employed. In particular,the aldehyde is preferably formaldehyde, paraformaldehyde or a mixtureof these. While one of the features of the method according to thepresent invention resides in the point that the acidic catalyst of ahigh concentration is employed as described later, paraldehyde isdepolymerized under such a condition when paraformaldehyde which is apolymer of formaldehyde is employed as the aldehyde, and hence it isconceivably formaldehyde that substantially contributes to the reaction.The type of the used aldehyde and the loading thereof are preferably soselected that the aldehyde is dissolved in the aqueous medium in thereaction.

While the phenolic compound is not particularly restricted, phenol,naphthol, hydroquinone, resorcin, xylenol and pyrrogallol can be listed,for example. The phenolic compound may be one type, or at least twotypes may be combined and employed. In particular, the phenolic compoundis preferably phenol, in consideration of the balance between solubilityin water and the performance of the obtained phenol resin and the cost.The type of the used phenolic compound and the loading thereof arepreferably so selected that the phenolic compound is dissolved in theaqueous medium in the reaction.

More specifically, the loading (feed quantity) of the phenolic compoundis preferably so selected that the concentration (weight ratio) of thephenolic compound with respect to the total weight of the reactionliquid is not more than 10 weight % when phenol or the like is employedas the phenolic compound, for example. When a phenolic compound(naphthol or the like, for example) having lower solubility in water isemployed, a lower concentration is desirably employed, in order toguarantee dissolution in the aqueous medium in the reaction and make thephenol resin powder exhibit excellent characteristics (a minute averageparticle diameter and a high single particle ratio, for example). The“total weight of the reaction liquid” denotes the total weight of thephenolic compound, the aldehyde, the acidic catalyst, the protectivecolloidal agent and the aqueous medium. The concentration of thephenolic compound with respect to the total weight of the reactionliquid is so set to not more than 10 weight % that temperature controlfrom the reaction initiation stage up to the phenol resin powder formingstage can be easily performed. In a case of initiating the reactionaround ordinary temperature, for example, no excessive heat generationresulting from runaway reaction or the like is caused particularly inthe initial stage of the reaction when the concentration of the phenoliccompound is set to not more than 10 weight %, whereby a phenol resinpowder having a small average particle diameter and inhibited fromsecondary aggregation can be formed while hardly performing temperaturecontrol. While the concentration (weight ratio) of the phenolic compoundwith respect to the total weight of the reaction liquid can be renderedhigher than 10 weight %, the temperature control in the reaction mustgenerally be properly performed in this case.

The loading (feed quantity) of the aforementioned aldehyde is preferablyso selected that the feed molar ratio of the phenolic compound withrespect to the aldehyde is not more than 0.9. The feed molar ratio ofthe phenolic compound with respect to the aldehyde is more preferablynot more than 0.75, further preferably not more than 0.5. The feed molarratio of the phenolic compound with respect to the aldehyde is so set tonot more than 0.9 that a phenol resin powder having a minute averageparticle diameter, inhibited from secondary aggregation, closer to aspherical shape, having a narrow particle size distribution and having asmall free phenol content can be formed. Further, secondary aggregationcan be further suppressed by setting the feed molar ratio of thephenolic compound with respect to the aldehyde to not more than 0.75. Inorder to render these characteristics related to the phenol resin powdermore excellent, the feed molar ratio of the phenolic compound withrespect to the aldehyde is particularly preferably set to not more than0.5. While the lower limit of the feed molar ratio of the phenoliccompound with respect to the aldehyde is not particularly restricted butthe feed molar ratio of the phenolic compound with respect to thealdehyde can be reduced by increasing the quantity of the aldehyde inthe range dissolved in the aqueous medium, for example, the feed molarratio of the phenolic compound with respect to the aldehyde ispreferably at least 0.1 in consideration of the use efficiency of theraw material.

While the aforementioned aldehyde and the phenolic compound are reactedin the aqueous medium in this step, one of the features of theproduction method according to the present invention resides in thepoint that this reaction is performed with the acidic catalyst of a highconcentration. This acidic catalyst is preferably a strong acidiccatalyst. For example, hydrochloric acid, phosphoric acid and sulfuricacid can be listed as such a catalyst. In particular, hydrochloric acidis more preferable, in consideration of easiness in removal or sidereaction in a case where the same remains. Acid with relatively highboiling point such as phosphoric acid or sulfuric acid can also besufficiently used depending on the use of the phenol resin powder. The“high concentration” specifically means that the molar concentration ofthe acidic catalyst in the reaction liquid is at least 2.0 mol/L, morepreferably at least 3 mol/L when the reaction is initiated aroundordinary temperature. In the case of employing hydrochloric acid as theacidic catalyst, the “molar concentration of hydrochloric acid in thereaction liquid” denotes the concentration of hydrogen chloride in thereaction liquid. In order to obtain a phenol resin powder having a smallaverage particle diameter and inhibited from secondary aggregation,particularly a phenol resin powder closer to a spherical shape, having anarrow particle size distribution and having a small free phenol contentin addition thereto, the molar concentration of the acidic catalyst inthe reaction liquid must be set to at least 2.0 mol/L when initiatingthe reaction around ordinary temperature. In view of a reaction ratesuitable for industrial production and acid resistance of relatedfacilities, the molar concentration of the acidic catalyst is preferablynot more than 6 mol/L. The starting temperature for the reaction is sorendered higher than ordinary temperature that the molar concentrationof the acidic catalyst necessary for attaining an equivalent reactionrate is slightly lower than that in a case where the reaction startingtemperature is around ordinary temperature.

Another feature of the production method according to the presentinvention resides in the point that the reaction between the aldehydeand the phenolic compound is performed in the presence of the protectivecolloidal agent. The protective colloidal agent contributes to formationof the phenol resin powder. In order to form a phenol resin powderhaving a small average particle diameter and inhibited from secondaryaggregation, particularly a phenol resin powder closer to a sphericalshape, having a narrow particle size distribution and having a smallfree phenol content in addition thereto, it is necessary to use such aprotective colloidal agent. In the present invention, a water-solubleprotective colloidal agent is preferably used as the protectivecolloidal agent. For example, a water-soluble polysaccharide derivativecan be suitably employed as the water-soluble protective colloidalagent. Specific examples of the suitably employable water-solublepolysaccharide derivative include alkaline metal salt or ammonium saltof carboxymethyl cellulose; natural starch adhesives mainly composed ofa water-soluble polysaccharide derivative such as gum arabic, acacia,guar gum or locust bean gum. While the degree of carboxymethylation ofcellulose is not particularly restricted when alkaline metal salt orammonium salt of carboxymethyl cellulose is used, a product having adegree of carboxymethylation of about 75% is put on the market, and thiscan be suitably employed. When the protective colloidal agent isobtained as dry powder, this may be directly added to and dissolved inthe reaction liquid, or an aqueous solution of the protective colloidalagent may be previously prepared and this may be added to the reactionliquid.

The loading of the aforementioned protective colloidal agent, notparticularly restricted, is preferably 0.01 to 3 weight % of the loadingof the aforementioned phenolic compound in solid weight. If the loadingof the protective colloidal agent is less than 0.01 weight %, it isinsufficient for setting the average particle diameter of the phenolresin particles to not more than 20 μm, and particle size control withanother parameter such as the loading of the phenolic compound or a rateof stirring, for example, is required. In order to set the averageparticle diameter of the phenol resin particles to not more than 10 μm,the loading of the protective colloidal agent is preferably set to atleast 0.04 weight % of the loading of the phenolic compound. If theloading of the protective colloidal agent is larger than 3 weight % ofthe loading of the phenolic compound, the separation rate tends to lowerin the separating-washing step described later due to viscosity increaseof the reaction liquid, and attention is required. It is to be speciallymentioned that the average particle diameter of the phenol resinparticles can be controlled by adjusting the loading of the protectivecolloidal agent if the loading of the protective colloidal agent is inthe aforementioned range, particularly the loading of the protectivecolloidal agent is 0.02 to 1 weight % of the loading of the phenoliccompound.

While water or a mixed solvent of water and an aqueous organic solventcan be listed as the aforementioned aqueous medium, a water solvent ispreferably employed in the present invention. The loading of the aqueousmedium is so selected that the concentration of the acidic catalyst isin the aforementioned range, and preferably so selected that theconcentration of the phenolic compound is further in the aforementionedpreferable range.

Specific methods for performing reaction with the aforementionedaldehyde, the phenolic compound, the acidic catalyst and the protectivecolloidal agent are now described. The following two methods can belisted as the specific methods for the reaction: (i) A method ofpreparing a mixed liquid by mixing the acidic catalyst, the protectivecolloidal agent and the aldehyde into the aqueous medium and thereafteradding the phenolic compound while stirring the mixed liquid, and (ii) amethod of preparing a mixed liquid by mixing the protective colloidalagent, the aldehyde and the phenolic compound into the aqueous mediumand thereafter adding the acidic catalyst while stirring the mixedliquid.

In each of the aforementioned methods (i) and (ii), the aforementionedmixed liquid is preferably a substantially homogeneous solution. Inother words, the solutes mixed into the aqueous medium are preferablycompletely dissolved, or at least substantially completely dissolved. Inthe preparation of the mixed liquid, the order of mixing is notparticularly restricted. The temperature for initiating the reaction ofthis mixed liquid, not particularly restricted, is preferably about 10to 50° C., more preferably about 20 to 40° C.

In the aforementioned method (i), the reaction between the aldehyde andthe phenolic compound is performed by adding the phenolic compound whilestirring the aforementioned mixed liquid. The addition of the phenoliccompound may be performed by directly adding the phenolic compound tothe mixed liquid, or the phenolic compound may be previously dissolvedin water, so that this aqueous solution is added to the mixed liquid.This reaction is preferably so controlled that the reaction temperatureis about 10 to 60° C., preferably about 20 to 50° C. The reaction ratetends to be small if the reaction temperature is less than about 10° C.,while there is a possibility of causing coarseness of the particlediameter or increase of the quantity of secondary aggregates if thereaction temperature exceeds 60° C. The temperature for initiating thereaction of the aforementioned mixed liquid is so set to about 20 to 30°C. around ordinary temperature and the concentration of the phenoliccompound with respect to the total weight of the reaction liquid is soset to not more than 10 weight % as to cause no excessive heatgeneration, whereby the reaction can be performed in the aforementionedpreferable temperature range while hardly performing temperaturecontrol.

In the aforementioned method (ii), the reaction between the aldehyde andthe phenolic compound is performed by adding the acidic catalyst whilestirring the aforementioned mixed liquid. The addition of the acidiccatalyst may be performed at once, or may be performed by dropping overa constant time. Further, the addition of the acidic catalyst may beperformed by directly adding the acidic catalyst to the mixed liquid(when employing hydrochloric acid as the acidic catalyst, concentratedhydrochloric acid may be directly added, for example), or the acidiccatalyst (concentrated hydrochloric acid, for example) may be dilutedwith water, so that the diluted solution of the catalyst is added to themixed liquid. The reaction temperature is preferably controlled to beabout 10 to 60° C., preferably about 20 to 50° C., similarly to the caseof the aforementioned (i).

While the reaction liquid is gradually clouded (suspended) and thephenol resin powder is formed as the reaction progresses in each of theaforementioned methods (i) and (ii), such clouding typically takes placeafter several 10 seconds to several minutes after the addition of thephenolic compound or the acidic catalyst. There is such a tendency thatthe time required for the clouding, i.e., precipitation of the phenolresin particles is shorter in the method (ii) than the method (i). Whilethe reaction liquid typically turns pale pink to dark pink after theclouding, the reaction is preferably continued until such coloring isobserved in the present invention. The time up to the coloring after theclouding is generally about several 10 minutes to several hours. Whileit has been necessary to stop stirring after precipitation of the phenolresin particles in the method described in the aforementioned PatentDocument 1 in order to prevent the particles from aggregating into theform of sticky clumps, the stirring can be continuously performed assuch also after precipitation of the phenol resin particles according tothe inventive production method employing the protective colloidalagent.

According to the inventive production method, therefore, the temperatureof the reaction liquid can be more strictly controlled, and the reactionliquid can be subjected to the subsequent non-thermofusibilizing step ina state where the degree of polymerization and the degree ofcrosslinking of the phenol resin are uniform. This can contribute to thehomogeneity of the finally obtained phenol resin powder.

(2) Non-Thermofusibilizing Step

In this step, the phenol resin powder is rendered non-thermofusible byheating the reaction liquid containing the aforementioned phenol resinpowder. Such non-thermofusibility is brought by crosslinking andhardening of the resin resulting from the heating. The heatingtemperature for the reaction liquid in this step is preferably at least60° C., more preferably at least 70° C. Further, the heating temperaturefor the reaction liquid is preferably not more than 100° C., morepreferably not more than 90° C. If the heating temperature is less than60° C., there is a possibility that sufficient non-thermofusibility isnot obtained. The sufficient non-thermofusibility mentioned here meansthat the phenol resin powder has the “non-thermofusibility” defined inthe above. If the heating temperature exceeds 100° C., on the otherhand, there is a possibility that a reactor having a condenser isrequired or acid resistance of related facilities should be taken intoconsideration. Even if the heating temperature is at a relatively lowlevel of about 60° C., sufficient non-thermofusibility can be suppliedby providing a sufficient retention time. The phenol resin powder can beadjusted to a desired degree of polymerization and a desired degree ofcrosslinking in response to the use by adjusting the heating temperatureand the heating time in the aforementioned preferable ranges.

The heating time, not particularly restricted so far as sufficientnon-thermofusibility can be supplied to the phenol resin powder, istypically about several minutes to several hours, depending on theheating temperature. When advancing to the subsequent step aftertermination of this heat treatment, the reaction liquid may be cooled toa proper temperature, or the process may advance to the subsequent stepas such without cooling the reaction liquid.

(3) Separating-Washing Step

In this step, the obtained non-thermofusible phenol resin powder isseparated from the reaction liquid and washed. Filtration orcompression, for example, can be suitably employed as the separatingmethod. As an apparatus for such a separating operation, a filter, acentrifugal dehydrator, a belt press or a filter press can be employed,for example. A separating method utilizing evaporation such asreduced-pressure distillation or spray drying has a possibility ofdamaging the apparatus due to the reaction liquid containing the acidiccatalyst of the high concentration. When performing the separatingoperation by filtration, a filter aid such as diatomaceous earth or aflocculant may be employed. The phenol resin powder according to thepresent invention has specific gravity of about 1.2 to 1.3 and sedimentsby still standing, and hence a preliminary operation such as decantationmay be performed in advance of this separating operation.

Then, the separated phenol resin powder is washed. The reactionsubstantially completely terminates by this washing operation. As aspecific method for the washing, (i) a method of adding a washingsolution to a phenol resin cake separated by the aforementionedseparating operation (pouring the washing solution on the separatedphenol resin cake on the filter and removing the washing solution by gaspurge or suction, for example), or (ii) a method of dispersing theseparated phenol resin cake in the washing solution and thereafterperforming the separating operation again can be listed, for example. Asthe washing solution, water can be suitably employed. The acidiccomponent can be removed from the phenol resin cake by washing the samewith water.

As a part of the washing operation, or in place of the aforementionedwashing operation with water, neutralization reaction may be performedby bringing the phenol resin cake into contact with an aqueous solutionexhibiting basicity. The neutralization reaction is so performed thatthe acidic catalyst component contained in the phenol resin cake can beeffectively removed. As the aqueous solution exhibiting basicityemployed for the neutralization reaction, an organic or inorganic weakbasic solution is preferably employed. When employing a strong basicrich solution, there is a possibility that the phenol resin particlesare discolored or dissolved. As the weak basic solution, a dilutedsolution of ammonia can be suitably employed, for example. This isbecause, when employing the diluted solution of ammonia, formed salt iswater-soluble and hence this salt can be removed by water washing whilethe ammonia itself can be sublimated/removed by heating.

In order to extract/separate chlorine ions infiltrating into the phenolresin powder by the reaction, the separated phenol resin powder ispreferably washed with an alcohol and/or an alkaline solution. In orderto efficiently perform extraction/separation of the chlorine ions, theaforementioned washing with water for washing out the reaction liquidfrom the surface of the phenol resin or an operation of neutralizing thechlorine ions on the surface of the phenol resin with an alkalinesolution may also be employed.

A washing solvent (washing solution medium) employed forextracting/separating the chlorine ions may be either the alcohol or thealkaline solution, or both may be employed. The chlorine ion content inthe non-thermofusible phenol resin powder can be effectively reduced bythe washing with the alcohol and/or the alkaline solution. Morespecifically, the chlorine content in the non-thermofusible phenol resinpowder can be reduced to not more than 500 ppm, and it is also possibleto reduce the chlorine content to not more than 100 ppm or lower thanthis.

It is to be specially mentioned that the chlorine ion content in thenon-thermofusible phenol resin powder can be reduced by washing the samewith the alcohol and/or the alkaline solution since the average particlediameter of the non-thermofusible phenol resin powder is sufficientlyminute and the single particle ratio is high. In other words, it isdifficult to reduce the chlorine content by washing thenon-thermofusible phenol resin powder with the alcohol and/or thealkaline solution if the average particle diameter of thenon-thermofusible phenol resin powder is large or the single particleratio is low. Also in this point, therefore, it is required in thepresent invention that the average particle diameter of thenon-thermofusible phenol resin powder is not more than 20 μm and thesingle particle ratio is at least 0.7.

As a preferred example of a specific method of the washing with thealcohol and/or the alkaline solution, a method of dispersing thenon-thermofusible phenol resin powder separated from the reaction liquidin the washing solvent (washing solution medium) and stirring the samefor a constant time can be listed. As hereinabove described, thenon-thermofusible phenol resin powder separated from the reaction liquidmay be previously prewashed with water or the like in advance of thewashing with the alcohol and/or the alkaline solution. As a method ofthe prewashing, a method of dispersing the non-thermofusible phenolresin powder separated from the reaction liquid in a liquid medium suchas water, for example, and stirring the same under ordinary temperatureto a temperature of less than 100° C. can be listed. More preferably,heated water is employed for the prewashing. However, although thechlorine content can be reduced to some extent by this prewashing, it isimpossible to reduce the chlorine content to not more than 500 ppm byonly this prewashing or an extremely long time is required for reducingthe chlorine content to not more than 500 ppm, and hence the washingwith the alcohol and/or the alkaline solution is preferably performed,in order to sufficiently reduce the chlorine content.

The alcohol is not particularly restricted, but methanol, ethanol,n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol,s-butyl alcohol, t-butyl alcohol, ethylene glycol, diethylene glycol,triethylene glycol and propylene glycol can be listed, for example. Asdescribed later, the glass transition temperature of thenon-thermofusible phenol resin powder according to the present inventionis about 80 to 200° C., and if the extracting operation with the alcoholis performed in a region exceeding this temperature, the rate ofextraction is remarkably increased. When performing extraction ofchlorine with an alcohol having a low boiling point in such a preferredtemperature region, an autoclave or the like must be used. Whenemploying an alcohol having a high boiling point, the extractingoperation in the aforementioned preferable temperature region can beperformed at ordinary temperature, while a drying operation after thewashing (extraction) can be complicated. In consideration of thesepoints, ethylene glycol, having a well-balanced boiling point withrespect to the glass transition temperature of the non-thermofusiblephenol resin and allowing a simple washing (extracting) operation and asimple drying operation among the illustrated alcohols, can bepreferably employed. As to the alcohol, only one type may be employed,or at least two types may be employed together.

The loading of the alcohol, not particularly restricted, can be set toat least 200 parts by weight with respect to 100 parts by weight of thesolid content of the non-thermofusible phenol resin powder separatedfrom the reaction liquid, for example.

Preferably, the washing temperature in the washing treatment employingthe alcohol is equal to or exceeds the glass transition temperature ofthe non-thermofusible phenol resin powder, more preferably a temperatureexceeding the glass transition temperature. The washing is so performedat the temperature being equal to or exceeding the glass transitiontemperature as to convert the non-thermofusible phenol resin powder to arubber state, whereby the chlorine (particularly chlorine ions)contained in this phenol resin powder can be effectively extracted intothe alcohol. The upper limit of the washing temperature, notparticularly restricted, is preferably set to not more than 250° C., inorder to avoid pyrolysis of the non-thermofusible phenol resin powderand the alcohol. The glass transition temperature of thenon-thermofusible phenol resin powder according to the present inventionis generally about 80 to 200° C.

A pressure condition in the washing with the alcohol is not particularlyrestricted, but the washing can be performed under ordinary pressure orunder pressurization. When employing an alcohol having a relatively lowboiling point, for example, the washing can be performed underpressurization, in order to set the washing temperature to a level beingequal to or exceeding the glass transition temperature of thenon-thermofusible phenol resin powder. The washing time, i.e., thestirring time for the non-thermofusible phenol resin powder dispersionliquid is not particularly restricted, but can be set to several minutesto several 10 hours, for example.

The aforementioned washing with the alcohol may be performed only once,or may be repeated a plurality of times, in order to attain the desiredchlorine content.

The alkaline solution in the washing with the alkaline solution, notparticularly restricted, is preferably a weak alkaline solution. Whenemploying a strong alkaline rich solution, there is a possibility thatthe phenol resin particles are discolored or dissolved. Further, inaddition to the above, a hydroxide solution of alkaline metal oralkaline earth metal, whose ionic component is nonvolatile, has apossibility of remaining also by the drying operation after the washing.As the weak alkaline solution, an ammonia solution, a pyridine solutionor a dimethylamine solution can be suitably employed, for example. Inparticular, the ammonia solution, having high chlorine ion removability,is more preferable. The ammonia concentration in the ammonia solution,not particularly restricted, is preferably a concentration exceeding 0.5weight % to 30 weight %, more preferably 1 to 25 weight %. If theammonia concentration is not more than 0.5 weight %, the chlorine ionsin the phenol resin powder cannot be effectively extracted into theammonia solution. If the ammonia concentration exceeds 30 weight %, onthe other hand, there is a possibility that the phenol resin particlesare discolored or dissolved. If the ammonia concentration exceeds 30weight %, further, the vapor pressure is so high that a condenser isrequired or employment of an autoclave is required depending on thewashing temperature (extraction temperature).

The loading of the alkaline solution is not particularly restricted butcan be set to at least 200 parts by weight with respect to 100 parts byweight of the solid content of the non-thermofusible phenol resin powderseparated from the reaction liquid, for example, depending on theconcentration of the contained alkaline substance.

The washing temperature in the washing treatment employing the alkalinesolution is not particularly restricted, but the chlorine ions can beefficiently removed from the non-thermofusible phenol resin powder evenat a temperature of less than the glass transition temperature of thenon-thermofusible phenol resin powder. Needless to say, the washing maybe performed at a temperature being equal to or exceeding the glasstransition temperature of the non-thermofusible phenol resin powder. Itmay be generally possible to more effectively extract the chlorine in ashort time by washing the non-thermofusible phenol resin powder at thetemperature being equal to or exceeding the glass transitiontemperature. When performing the washing with the ammonia solution undera high temperature, an autoclave or the like is preferably used. Theupper limit of the washing temperature, not particularly restricted, ispreferably set to not more than 250° C., in order to avoid pyrolysis ofthe non-thermofusible phenol resin powder. The upper limit is morepreferably not more than 100° C.

The pressure condition in the washing with the alkaline solution is notparticularly restricted, but the washing can be performed under ordinarypressure or under pressurization. Further, the washing time, i.e., thestirring time for the non-thermofusible phenol resin powder dispersionliquid is not particularly restricted, but can be set to several minutesto several 10 hours, for example.

The aforementioned washing with the alkaline solution may be performedonly once, or may be repeated a plurality of times, in order to attaindesired chlorine content.

According to the present invention, it is also preferable to wash thenon-thermofusible phenol resin powder with both of the alcohol and thealkaline solution, in order to sufficiently reduce the chlorine content.In this case, “with both of the alcohol and the alkaline solution”includes i) a method of employing a mixed liquid of the alcohol and thealkaline solution as the washing solvent, ii) a method of washing thenon-thermofusible phenol resin powder with the alcohol and thereafterwashing the same with the alkaline solution, and iii) a method ofwashing the non-thermofusible phenol resin powder with the alkalinesolution and thereafter washing the same with the alcohol. Among these,the methods ii) and iii) are preferable, while the method iii) is morepreferable since the chlorine content can be sufficiently reduced and analkaline substance derived from the employed alkaline solution can alsobe removed.

In the present invention, a step (post-washing step) of washing thenon-thermofusible phenol resin powder with a liquid medium differentfrom the alcohol and the alkaline solution is preferably provided afterthe aforementioned washing with the alcohol and/or the alkalinesolution. This liquid medium preferably contains substantially no ionicimpurity, and pure water or ion-exchanged water can be listed as such aliquid medium, for example. The alcohol or the alkaline solutionadhering to the non-thermofusible phenol resin powder and salt formed bythe neutralization reaction between the alkaline solution and the acidiccatalyst are removed by this post-washing. Solid-liquid separationbetween the phenol resin powder and the washing solution after thewashing with the alcohol and/or the alkaline solution or after thepost-washing step can be performed similarly to the aforementionedseparating step.

The washed phenol resin powder can be used in the state containing theliquid medium without being dried, and such a non-thermofusible phenolresin powder containing the liquid medium also belongs to the range ofthe present invention. For example, a phenol resin powder containingwater can be used in a case of preparing a water dispersion liquid orthe like. Alternatively, a drying step may be provided after the washingstep. When employed as an organic filler, the non-thermofusible phenolresin powder is preferably dried. While the method of drying is notparticularly restricted, a method employing a tray type static dryer, aflash dryer or a fluidized-bed dryer can be listed, for example. Dryingis so performed that non-thermofusible phenol resin powder exhibitingexcellent fluidity with a liquid medium content of not more than about5% can be obtained. While a phenol resin powder having a high singleparticle ratio can be obtained according to the inventive method byperforming slight pulverizing if necessary, the single particle ratiomay be further improved with a pulverizer or the like in or after theaforementioned drying step.

According to the aforementioned inventive method for producing anon-thermofusible phenol resin powder, a non-thermofusible phenol resinpowder having an average particle diameter of not more than 20 μm,particularly not more than 10 μm, having a single particle ratio of atleast 0.7 and preferably having a chlorine content of not more than 500ppm can be produced by a relatively simple method and by a methodsuitable for mass production. According to the inventive productionmethod, further, a non-thermofusible phenol resin powder having thesecharacteristics as well as having a narrow particle size distribution,having spherical particles and having an extremely small free phenolcontent can be produced, and it is also possible to reduce the chlorineion content to not more than 100 ppm. Such a non-thermofusible phenolresin powder according to the present invention can be suitably employedfor a semiconductor use, for example.

<Thermosetting Resin Composition>

The thermosetting resin composition according to the present inventioncontains the aforementioned non-thermofusible phenol resin powderaccording to the present invention, epoxy resin and a hardening agent.The chlorine content in the non-thermofusible phenol resin powder ispreferably not more than 500 ppm. This thermosetting resin compositioncontains the inventive non-thermofusible phenol resin powder reduced inchlorine content, particularly in chlorine ion content, whereby the sameis supplied with high heat resistance, dynamical performance etc.belonging to the phenol resin, and can be suitably employed as a sealingmaterial for a semiconductor and an adhesive for a semiconductor. Thehigh heat resistance of the thermosetting resin composition not onlyresults from the high heat resistance belonging to the non-thermofusiblephenol resin powder itself, but also results from that thenon-thermofusible phenol resin powder and the epoxy resin form acomposite. In other words, the non-thermofusible phenol resin powder andthe epoxy resin form a tough composite due to reaction between ahydroxyl group of a phenol skeleton belonging to the non-thermofusiblephenol resin powder and a glycidyl group of the epoxy resin. Thestrength on the interface between the non-thermofusible phenol resinpowder and the epoxy resin increases due to the formation of such acomposite, whereby the thermosetting resin composition according to thepresent invention has extremely excellent heat resistance. It is alsoone factor for the high heat resistance that the difference between thelinear expansion coefficients of the non-thermofusible phenol resinpowder and the epoxy resin is small.

In the thermosetting resin composition according to the presentinvention, the loading of the non-thermofusible phenol resin powderwhich is an organic filler, not particularly restricted, can be set to20 to 900 parts by weight with respect to 100 parts by weight of thetotal quantity of the epoxy resin and a hardening agent therefor whenemploying the epoxy resin as binder resin, for example. When employingthe thermosetting resin composition as a sealing material for asemiconductor or an adhesive for a semiconductor, the loading of thenon-thermofusible phenol resin powder is preferably set to 60 to 500parts by weight, more preferably set to 300 to 400 parts by weight withrespect to 100 parts by weight of the total quantity of the epoxy resinand the hardening agent therefor. If the loading is less than 20 partsby weight with respect to 100 parts by weight of the total quantity ofthe epoxy resin and the hardening agent therefor, the effect ofsupplying heat resistance tends to be hard to obtain. If the loadingexceeds 900 parts by weight, on the other hand, a dense structure ishard to obtain since the phenol resin powder is non-thermofusible, andthe application is generally limited to a use requiring no denseness. Ifthe non-thermofusible phenol resin powder in a quantity exceeding 500parts by weight is added with respect to 100 parts by weight of thetotal quantity of the epoxy resin and the hardening agent therefor,excellent fluidity may not be obtained as the sealing material for asemiconductor or the adhesive for a semiconductor.

As the epoxy resin, a well-known one can be employed, and glycidyl ethertype epoxy resin of phenol can be suitably employed, for example.Specific examples are bisphenol A (or AD, S or F) glycidyl ether,hydrogenated bisphenol A glycidyl ether, ethylene oxide adduct bisphenolA glycidyl ether, propylene oxide adduct bisphenol A glycidyl ether,glycidyl ether of phenol novolac resin, glycidyl ether of cresol novolacresin, glycidyl ether of bisphenol A novolac resin, glycidyl ether ofnaphthalene resin, trifunctional (or tetrafunctional) glycidyl ether,glycidyl ether of dicyclopentadiene phenol resin, glycidyl ester ofdimer acid, trifunctional (or tetrafunctional) glycidyl amine andglycidyl amine of naphthalene resin. These can be used singly or in acombination of at least two types.

The hardening agent is added for hardening the aforementioned epoxyresin. The hardening agent for the epoxy resin is not particularlyrestricted, but a well-known one can be used. Specific examples are aphenolic compound, aliphatic amine, cycloaliphatic amine, aromaticpolyamine, polyamide, aliphatic acid anhydride, cycloaliphatic acidanhydride, aromatic acid anhydride, dicyandiamide, organic aciddihydrazid, boron trifluoride amine complex, imidazole and tertiaryamine, for example.

The loading of the hardening agent, not particularly restricted, can beset in the range generally used in this field, and can be set to 5 to200 parts by weight with respect to 100 parts by weight of the epoxyresin, for example. However, the hardening agent, generally added by aweight corresponding to the epoxy equivalent of the epoxy resin, ispreferably added by a loading slightly smaller than the weightcorresponding to the epoxy equivalent in the present invention. This isbecause the non-thermofusible phenol resin powder reacts with theglycidyl group of the epoxy group on the surface thereof or in thevicinity of the surface as hereinabove described and hence the hardeningagent is rendered excessive if the hardening agent is added by the epoxyequivalent. The excess hardening agent may exert bad influence such asreduction of a thermophysical property or a bleed. The quantity to bereduced, not necessarily sayable since the same depends on the type ofthe epoxy resin, the loading of the non-thermofusible phenol resinpowder, the type of the hardening agent and the like, can be set toabout 5 to 10% of the weight corresponding to the epoxy equivalent ofthe epoxy resin.

The thermosetting resin composition according to the present inventionmay further contain a hardening accelerator. As the hardeningaccelerator, a well-known one can be used, and imidazole, dicyandiamidederivative, dicarboxylic acid dihydrazid, triphenylphosphine,tetraphenylphosphonium tetraphenylborate, 2-ethyl-4-methylimidazole-tetraphenylborate and1,8-diazabicyclo[5.4.0]undecene-7-tetraphenylborate can be listed, forexample. The loading of the hardening accelerator, not particularlyrestricted, can be set to 0 to 30 parts by weight with respect to 100parts by weight of the epoxy resin, for example.

The thermosetting resin composition according to the present inventionmay contain another additive other than the above. For example, anantifoaming agent, a leveling agent, a coloring agent, a diluent(organic solvent or the like), a viscosity modifier, a surface activeagent, a light stabilizer, an antioxidant, a fire retardant assistant,thermoplastic resin and thermosetting resin other than the epoxy resincan be listed as another additive. The thermosetting resin compositionaccording to the present invention may further contain another organicfiller other than the non-thermofusible phenol resin powder according tothe present invention or an inorganic filler. For example, carbon and arubber-based filler (acrylonitrile butadiene rubber filler, siliconerubber filler or the like) can be listed as another organic filler. Onthe other hand, a metal filler such as silver powder, gold powder,copper powder and nickel powder; silica (fused silica, crushed silica orfumed silica), alumina, boron nitride, titania, glass, iron oxide,ceramic, calcium silicate and mica can be listed as the inorganicfiller.

The thermosetting resin composition according to the present inventioncan be obtained by mixing and kneading the non-thermofusible phenolresin powder, the epoxy resin, the hardening agent and another additiveadded if necessary with a triple roll mill or a ball mill.

When employing the thermosetting resin composition according to thepresent invention as an adhesive for a semiconductor, it is alsopreferable to mold the thermosetting resin composition into a film, inorder to improve workability in semiconductor production or the like. Asa method for preparing an adhesive film, a method of forming a layer ofthe resin composition by applying the thermosetting resin compositiononto a substrate, drying the same and thereafter removing the substratecan be listed, for example. The drying temperature, not particularlyrestricted, can be set to about 50 to 200° C., for example.

<Carbon Electrode Material Powder>

According to the present invention, a carbon electrode material powderhaving an extremely minute particle diameter, having a narrow particlesize distribution and hardly containing secondary aggregates resultingfrom aggregation of these minute primary particles, i.e., having a highsingle particle ratio is provided. Such a carbon electrode materialpowder according to the present invention, improved in capacitance perunit volume and output density, can be suitably employed as an electrodematerial for an electric double layer capacitor, a lithium ion batteryand a lithium ion capacitor.

The lithium ion battery is generally charged/discharged by using acarbonaceous material for a negative electrode, using alithium-containing compound for a positive electrode and moving lithiumions between the positive electrode and the negative electrode. Theelectric double layer capacitor is charged/discharged byadsorption/desorption of electrolytic ions by using carbonaceousmaterials having relatively large specific surface areas for a positiveelectrode and a negative electrode. In a recently proposed lithium ioncapacitor, a carbonaceous material, having a relatively large specificsurface area, similar to that of an ordinary capacitor is used for apositive electrode, while a carbonaceous material similar to that of thelithium ion battery is used for a negative electrode. The lithium ioncapacitor, charged/discharged by adsorption/desorption of lithium ionsand electrolytic ions, is noted as a new type of capacitor improving theenergy density of the electric double layer capacitor.

In order to further improve the performance of the lithium ion battery,the electric double layer capacitor and the lithium ion capacitor,development of a carbon electrode material improved in performance,i.e., a carbon electrode material having a high capacitance per unitvolume and a high output density is indispensable. In general, variousstudies have been made in order to obtain such a carbon electrodematerial improved in performance, and carbon material powders havingsmall particle diameters have been proposed in order to improve afilling property per unit volume or to improve a contact interface areawith an electrolyte. However, none can be regarded as having asufficient spatial filling property, and hence further improvement hasbeen required as to the carbon electrode material, in order to obtain alithium ion battery or the like further improved in performance.

The carbon electrode material powder according to the present inventionis characterized in that the average particle diameter is not more than10 μm, the single particle ratio is at least 0.7, and the coefficient ofvariation of the particle size distribution expressed in the aboveformula [1] is not more than 0.65. The sphericity of the carbonelectrode material particles is preferably at least 0.5. According tothe present invention, a carbon electrode material powder mixtureobtained by mixing at least two types of carbon electrode materialpowders according to the present invention having different averageparticle diameters is provided.

The carbon electrode material powder according to the present inventionis now described in detail. In the carbon electrode material powderaccording to the present invention, the average particle diameter of theparticles (also referred to as primary particles, as a term with respectto the secondary aggregates) is not more than 10 μm. The averageparticle diameter is so reduced to not more than 10 μm that the outersurface areas of the carbon particles enlarge. Thus, the infiltrationfrequency of lithium ions or electrolytic ions into the carbon particlesincreases, while the diffusion length of these ions in the carbonelectrode material shortens, whereby the comings and goings of the ionsin charging/discharging quicken, and the output density can be improvedas a result. Further, it is possible to improve the filling density ofthe carbon electrode material by combining a carbon electrode materialhaving a smaller average particle diameter and a larger carbon electrodematerial with each other at a proper ratio as described later, wherebythe capacitance per unit volume can be increased. While the lower limitof the average particle diameter is not particularly restricted,solid-liquid separation may be rendered difficult in production ofnon-thermofusible phenol resin particles preferably employed as the rawmaterial for the carbon electrode material powder according to thepresent invention if the same is excessively minute. If the averageparticle diameter is excessively minute, further, a slurry may causereduction of fluidity based on dilatancy and reduction of coatingefficiency may be observed when producing an electrode coated withactivated carbon by using the carbon electrode material powder forpreparing the slurry and applying this onto a collector. In such aviewpoint, therefore, the average particle diameter of the carbonelectrode material powder is preferably at least 0.5 μm, more preferablyat least 1 μm.

The “average particle diameter” of the carbon electrode material powderhas the same meaning as the “average particle diameter” as to the phenolresin powder defined in the above.

The carbon electrode material powder according to the present inventionhas a narrow particle size distribution, and more specifically, thecoefficient of variation of the particle size distribution of theparticles (primary particles) constituting the carbon electrode materialpowder according to the present invention is not more than 0.65. Thecoefficient of variation of the particle size distribution is morepreferably not more than 0.6. The “coefficient of variation of theparticle size distribution” has the same meaning as the “coefficient ofvariation of the particle size distribution” as to the phenol resinpowder defined in the above, i.e., denotes a value calculated accordingto the above formula [1].

While it is possible to improve the filling density of the carbonelectrode material by combining the carbon electrode material having thesmaller average particle diameter and the larger carbon electrodematerial with each other at the proper ratio as hereinabove described,it is difficult to obtain a sufficiently high filling density and hencethe improvement of the capacitance is insufficient if the particle sizedistributions of these carbon electrode material powders are wide (thecoefficients of variation exceed 0.65).

The single particle ratio of the carbon electrode material powderaccording to the present invention is at least 0.7, preferably at least0.8. If the single particle ratio is less than 0.7 and a large quantityof secondary aggregates are present, clearances are formed between theprimary particles, and the filling density lowers. Particularly whencarbon electrode materials having different average particle diametersare so mixed with each other as to improve the filling density, itbecomes difficult to fill up the clearances between the primaryparticles with the carbon electrode material having the smaller averageparticle diameter, and hence not only the filling density cannot beimproved but also the fluidity of the slurry tends to lower when thecarbon electrode material is slurried with an electrolyte. The “singleparticle ratio” of the carbon electrode material powder has the samemeaning as the “single particle ratio” as to the phenol resin powderdefined in the above.

FIG. 8 shows a scanning electron micrograph (hereinafter referred to asan SEM photograph) of a preferred example of the carbon electrodematerial powder according to the present invention. As shown in FIG. 8,the carbon electrode material powder according to the present inventionis a phenol resin powder having minute particle diameters, has a smallquantity of secondary aggregates resulting from aggregation of theparticles (primary particles), and exhibits a narrow particle sizedistribution. The carbon electrode material powder shown in FIG. 8 hasan average particle diameter of 4 μm, a single particle ratio of 0.98and a coefficient of variation of the particle size distribution of0.51.

The particle shape of the carbon electrode material powder according tothe present invention is preferably as close to a spherical shape aspossible. More specifically, the sphericity is preferably at least 0.5,more preferably at least 0.7, particularly preferably at least 0.9. Asthe particle shape is closer to the spherical shape, i.e., as thesphericity is closer to 1.0, the filling density of the carbon electrodematerial powder can be more improved, and fluidity of a slurry in a caseof slurrying the carbon electrode material with an electrolyte can bemore improved. The “spherical shape” has the same meaning as the“spherical shape” as to the phenol resin powder defined in the above.

The specific surface area of the carbon electrode material powderaccording to the present invention measured according to the BET methodby nitrogen adsorption, not particularly restricted, is preferably 1 to500 m²/g, more preferably 1 to 200 m²/g, further preferably 1 to 50 m²/gif the carbon electrode material powder is used as a negative electrodematerial for a lithium ion battery or a lithium ion capacitor. If thespecific surface area exceeds 500 m²/g, the ratio of a dischargecapacity with respect to a charge capacity tends to lower. If the carbonelectrode material powder is used as an electrode material for anelectric double layer capacitor, the specific surface area is preferably600 to 2300 m²/g, more preferably 800 to 2000 m²/g. Infiltration ofelectrolytic ions into pores tends to be not smoothly performed if thespecific surface area is less than 600 m²/g, while it follows that largepores other than the pores utilized for adsorption/desorption of theelectrolytic ions are formed and there is such a tendency that thedensity of the electrode material lowers and no sufficient capacitancecan be ensured if the specific surface area exceeds 2300 m²/g.

The raw material for the carbon electrode material powder according tothe present invention is not particularly restricted so far as a carbonelectrode material having the aforementioned specific characteristicscan be obtained, but a well-known raw material can be used. As such araw material, thermosetting resin such as phenol resin, melamine resin,urea resin and epoxy resin can be listed, for example. The carbonelectrode material powder is preferably obtained by firing (carbonizing)and/or activating a powder of this resin. The phenol resin is preferablein a point of a residual carbon ratio among the aforementioned resins,and the aforementioned non-thermofusible phenol resin powder accordingto the present invention is particularly preferably employed.

When employing the non-thermofusible phenol resin powder according tothe present invention as the raw material for the carbon electrodematerial powder, the boiling methanol solubility thereof is preferablyless than 30%, more preferably less than 20%. While the sphericity andthe single particle ratio of the carbon electrode material powder can bebasically controlled by adjusting the raw material composition andreaction conditions in production of the phenol resin powder serving asthe raw material, the sphericity and the single particle ratio of theobtained carbon electrode material powder can be improved also byemploying a phenol resin powder whose boiling methanol solubility isless than 30%.

Further, the free phenol content in the non-thermofusible phenol resinpowder serving as the raw material is preferably not more than 500 ppm.This free phenol content is more preferably not more than 300 ppm,further preferably not more than 200 ppm. The free phenol content is soset to not more than 500 ppm that formation of fine cracks following thefiring and reduction of the residual carbon ratio can be suppressed oravoided, and a carbon electrode material powder having a sharp pore sizedistribution after activation can be obtained. Further, the free phenolis harmful to the human body and the environment, and hence such aphenol resin powder is so employed that a production method having highsafety with respect to the human body and the environment is provided.

When employing the carbon electrode material powder according to thepresent invention as an electrode material for an electric double layercapacitor, a lithium ion battery and a lithium ion capacitor, at leasttwo types of carbon electrode material powders having different averageparticle diameters may be mixed and employed. According to the inventiveproduction method described later, the average particle diameter of thecarbon electrode material powder can be controlled to a desired value,whereby a carbon electrode material powder having a desired averageparticle diameter as well as a sharp particle size distribution and ahigh single particle ratio can be provided. The “types” in “at least twotypes” denotes the difference between the average particle diameters. Atleast two types of carbon electrode material powders having differentaverage particle diameters are so mixed and employed that the carbonelectrode material having the smaller average particle diameter canenter clearances of the carbon electrode material having the largeraverage particle diameter, whereby the filling density of the carbonelectrode material can be improved. The optimum mixing ratio in the caseof mixing at least two types of carbon electrode material powders havingdifferent average particle diameters, depending on the average particlediameters etc. of these carbon electrode materials, cannot be generallydetermined, but is preferably so properly set that the capacitance perunit volume most increases in response to the average particle diametersetc. of the mixed carbon electrode materials.

In the case of obtaining a carbon electrode material mixture by mixingat least two types of carbon electrode material powders having differentaverage particle diameters, at least one carbon electrode materialcomponent must be the carbon electrode material according to the presentinvention. In order to effectively attain the effects of improving thefilling density and the output density, all carbon electrode materialcomponents are preferably the carbon electrode material according to thepresent invention. In other words, the average particle diameters of allmixed carbon electrode material components are so set to not more than10 μm that the output density of the carbon electrode material mixturecan be effectively improved as a whole. When the particle sizedistribution of each carbon electrode material component is sharp, itfollows that clearances constituted of particles having a larger averageparticle diameter exhibit a substantially constant magnitude and mixturedesign of mixing smaller particles having proper magnitudes capable offilling up the clearances is so enabled that the filling property of thecarbon electrode material mixture can be simply improved as a whole. Ina case of mixing electrode material components having wider particlesize distributions, on the other hand, it follows that clearancesconstituted of particles having a larger average particle diameter aredistributed in various magnitudes, while it is difficult to producefiner particles having particle size distributions for properly fillingup the clearances of such various magnitudes. Even if it is possible toobtain electrode material components having such complicated particlesize distributions, such an inconvenience takes place that a specificmixing operation is necessary for storing all particles in clearancescorresponding to the respective particle diameters or a long time isrequired for the mixing. In view of improvement in the filling property,all carbon electrode components are preferably close to a sphericalshape (sphericity of at least 0.5).

A method for producing the carbon electrode material powder is nowdescribed. The following method for producing a carbon electrodematerial powder according to the present invention is suitably employedas a method for producing the aforementioned carbon electrode materialpowder according to the present invention. According to the inventivemethod, the average particle diameter of the obtained carbon electrodematerial powder can be controlled by adjusting the concentration of aprotective colloidal agent. According to the inventive method, further,a carbon electrode material having a minute average particle diameter, anarrow particle size distribution and a high single particle ratio canbe obtained without performing mechanical crushing on a phenol resinserving as an intermediate material and the carbon electrode material.

The method for producing a carbon electrode material powder according tothe present invention includes the following steps (a) to (d):

(a) A phenol resin powder forming step of forming a phenol resin powderby reacting an aldehyde and a phenolic compound in an aqueous medium inthe presence of an acidic catalyst having a molar concentration of atleast 2.0 mol/L in a reaction liquid and a protective colloidal agent,

(b) a non-thermofusibilizing step of forming a non-thermofusible phenolresin powder by heating the reaction liquid containing the phenol resinpowder,

(c) a separating step of separating the non-thermofusible phenol resinpowder from the reaction liquid, and

(d) a firing step of firing the non-thermofusible phenol resin powder.

While the respective steps are now described in detail, the steps (a) to(c) are similar to those of the aforementioned method for producing anon-thermofusible phenol resin powder, and hence the same are describedwith partial omission.

A strong acidic catalyst such as hydrochloric acid, phosphoric acid orsulfuric acid is preferably employed as the acidic catalyst in thephenol resin powder forming step, and hydrochloric acid is morepreferable. This is because the hydrochloric acid is an acid in the formof gas and can be easily removed by a drying operation and henceoxidation reaction by a residual acid component less exerts badinfluence on surface chemical characteristics and strength of the phenolresin powder.

The loading of the protective colloidal agent in the phenol resin powderforming step is preferably set to at least about 0.04 weight % of theloading of the phenolic compound in solid weight. If the loading of theprotective colloidal agent is less than 0.04 weight %, it isinsufficient for setting the average particle diameter of the carbonelectrode material powder to not more than 10 μm, and particle sizecontrol with another parameter such as the loading of the phenoliccompound or a rate of stirring, for example, is required. The upperlimit of the loading of the protective colloidal agent, not particularlyrestricted, is preferably not more than 3 weight % of the loading of thephenolic compound. If the loading is larger than 3 weight %, theseparation rate tends to lower in the separating step or the likedescribed later due to viscosity increase of the reaction liquid,although a carbon electrode material powder having an average particlediameter of not more than 10 μm can be obtained.

After the separating step, a step of washing the separated phenol resinpowder may be provided. As a specific method for the washing, (i) amethod of adding a washing solution to a phenol resin cake separated bythe aforementioned separating step (pouring the washing solution on theseparated phenol resin cake on a filter and removing the washingsolution by gas purge or suction, for example), or (ii) a method ofdispersing the separated phenol resin cake in the washing solution andthereafter performing the separating operation again can be listed, forexample. As the washing solution, water can be suitably employed. Theacidic component can be removed from the phenol resin cake by washingthe same with water.

As a part of the washing operation, or in place of the aforementionedwashing operation with water, neutralization reaction may be performedby bringing the phenol resin cake into contact with an aqueous solutionexhibiting basicity. The neutralization reaction is so performed thatthe acidic catalyst component etc. adhering to the surface of the phenolresin powder can be effectively removed. As the aqueous solutionexhibiting basicity employed for the neutralization reaction, an organicor inorganic weak basic solution is preferably employed. When employinga strong basic rich solution, there is a possibility that the phenolresin particles are discolored or dissolved. As the weak basic solution,an ammonia solution can be suitably employed, for example. Whenemploying the ammonia solution, formed salt is water-soluble, and hencethis salt can be removed by water washing. Further, a minute quantity ofresidual salt can also be sublimated/removed by heating.

In the non-thermofusible phenol resin powder obtained in theaforementioned manner, the coefficient of variation of the particle sizedistribution is typically not more than 0.65, and the single particleratio is at least 0.7. The average particle diameter can also be set toa desired value in the range of not more than 20 μm, for example, byadjusting the loading of the protective colloidal agent. The averageparticle diameter of the particles is reduced to some extent (typicallyby about 30 percent) by the subsequent firing step and/or an activatingstep, and hence the average particle diameter of the non-thermofusiblephenol resin powder must be controlled in consideration of this point.The characteristics (the average diameter, the particle sizedistribution, the single particle ratio etc.) of the carbon electrodematerial powder depend on the characteristics of the non-thermofusiblephenol resin powder which is the intermediate material. According to theinventive method, the characteristics of the non-thermofusible phenolresin powder can be controlled to proper ranges, whereby a carbonelectrode material powder having characteristics desirable as anelectrode material for an electric double layer capacitor, a lithium ionbattery and a lithium ion capacitor can be suitably obtained. Accordingto the aforementioned method, further, a non-thermofusible phenol resinpowder having an extremely small free phenol content (not more than 500ppm) can be produced. The carbon electrode material powder obtained withsuch a non-thermofusible phenol resin powder has a sharp pore sizedistribution.

The firing step is now described. The firing (carbonization) of thenon-thermofusible phenol resin powder is performed under a non-oxidizingatmosphere of inert gas such as nitrogen, argon or helium in atemperature range of 500 to 2500° C., preferably 500 to 1200° C., morepreferably 550 to 1000° C. When performing an activation treatment afterthe firing step, the firing temperature is preferably set to not morethan about 900° C., so that activation can be efficiently progressed. Asan apparatus for performing the firing, a well-known apparatus such asan electric furnace or an external heating gas furnace can be employed,for example.

The activation treatment is performed continuously to the firing step,if necessary. The temperature for the activation treatment is 500 to1100° C., preferably 800 to 1000° C., more preferably 850 to 950° C. Ifthe temperature for the activation treatment is higher than 1100° C.,reduction of the residual carbon ratio or the like may result fromoxidation of the surface of the carbon electrode material or oxidationof the carbon skeleton. If the temperature is lower than 500° C., on theother hand, pore formation by the activation treatment does notsufficiently progress.

Oxygen, carbon dioxide, steam or mixed gas of at least two types ofthese, or atmosphere gas of nitrogen, argon or helium or combustion gasof methane, propane or butane containing such gas can be employed forthe activation treatment. The activation treatment is preferably soperformed that the weight reduction ratio of the carbon materialresulting from the activation is 5 to 90%. In a case of formingrelatively large pores referred to as mesopores, the activationtreatment may be performed by properly adding a metal such as nickel,cobalt or iron or a metallic compound. Further, chemical activation ofadding a chemical such as potassium hydroxide or zinc chloride may beperformed.

When performing the firing and/or the activation treatment by employingthe non-thermofusible phenol resin powder obtained through theaforementioned steps (a) to (c) as such, the phenol resin particles mayfly in a firing furnace or the like and these may be discharged alongwith exhaust gas, to cause reduction of the yield or reduction ofoperability. In this case, the primary particles may be granulated intoparticles having proper strength and magnitude, in advance of the firingstep. In the granulation, coal tar, pitch, creosote oil, liquefiedphenol resin, liquefied melamine resin, polyvinyl alcohol, starch,crystalline cellulose powder or methyl cellulose can be employed as abinder. These may be singly employed, or at least two types may becombined and employed.

The granulation can be performed by homogeneously mixing thenon-thermofusible phenol resin powder and the binder with each other ina mixer such as a kneader and thereafter molding the mixture into agranular substance with a wet extrusion granulator, a verticalgranulator, a semidry disc pelleter or a granulating machine. Themolding, generally performed at room temperature, may be executed underheating if the quantity of a pitch component or the like is large. Thegranulated substance, not particularly restricted in shape andmagnitude, can be worked into a columnar shape of about 0.5 to 5 mm indiameter and 1 to 10 mm in length or a spherical shape of about 0.1 to10 mm in diameter, for example. In order to improve the workability inthe mixing and the molding, a surface active agent such as ethyleneglycol, polyoxyethylene alkyl ether, polyoxyethylene fatty ester orpolycarboxylate ammonium salt, a hardening agent such as liquefiedthermosetting resin, a paste such as polyvinyl alcohol or a plasticizerfor extrusion granulation may be added, for example. The strength of thegranulated substance is at a level capable of holding the shape to someextent during the firing and/or the activation treatment andpulverizable after termination of these treatments. The pulverizing canbe performed with a crusher or a pulverizer such as a ball mill, avibration mill, a rotor mill, a hammer mill or a jet mill, for example.

<Molecular Sieve Carbon>

According to the present invention, a molecular sieve carbon suitablyemployed for a nitrogen generator, particularly a pressure swingadsorption (hereinafter abbreviated as PSA) nitrogen generator isprovided.

In recent years, pressure swing adsorption (PSA) has been developed andput into practice as the technique of separating nitrogen and oxygencontained in air from each other. The PSA is a method for separating aspecific component from source gas by filling up at least one adsorptiontower with an adsorbent such as a molecular sieve carbon andperiodically repeating selective adsorption under pressurization andreproduction of the adsorbent such as the molecular sieve carbon underdecompression or under ordinary pressure. The gas separating ability ofthe molecular sieve carbon is considered as resulting from thedifference between adsorption rates of respective adsorbed substances ina specific combination of an adsorbed substance having a moleculardiameter close to the pore diameter of the molecular sieve carbon and anadsorbed substance having a molecular diameter smaller than the same.

While a PSA nitrogen generator for air separation employing a molecularsieve carbon as an adsorbent is of an ordinary temperature separationsystem, advantageous in cost as compared with a cryogenic separationsystem nitrogen generator depending on the loading of nitrogen or usedpurity thereof and widely industrially employed, improvement inperformance of the PSA nitrogen generator, particularly the molecularsieve carbon is required in order to render the same usable for a largernumber of uses and in order to obtain nitrogen at a lower cost, andvarious molecular sieve carbons have been proposed in recent years.

However, although there is prior art mentioning a constant range of thediameters of carbon primary particles constituting a pellet-typemolecular sieve carbon, the average particle diameter of the carbonprimary particle diameters and the width of the particle sizedistribution thereof have not been heretofore taken into consideration.

This is because the density of an aggregate of carbon primary particleshaving a wide particle size distribution generally tends to be highdepending on the particle size distribution and such a property has beenconsidered as advantageously acting on the performance of the molecularsieve carbon. Further, the situation that it has been difficult toindustrially produce a resin material for a molecular sieve carbonhaving a particle size range controlled in units of several μm,particularly a spherical resin raw material and the situation that ithas been difficult to work the spherical resin raw material having theparticle size range controlled in units of several μm into a pellet-typemolecular sieve carbon of about 0.5 to 5 mm in particle diameterpreferable as an adsorbent can also be listed as the reasons therefor.In addition, the situation that the particle diameters cannot becontrolled in units of several μm in a case of reducing the particlediameters by crushing a raw material having large particle diameters andthe situation that a raw material in units of several μm cannot beclassified into a narrow particle size distribution even ifclassification or the like is employed for controlling the particle sizedistribution and hence it has been difficult to industrially narrow theparticle size distribution of the raw material having the particlediameters in units of several can also be listed as the reasons.

According to the present invention, a molecular sieve carbon employingcarbon particles exhibiting minute particle diameters and having anarrow particle size range as primary particles and enabling remarkableimprovement in efficiency as compared with a conventional molecularsieve carbon is provided.

In other words, the molecular sieve carbon according to the presentinvention is a molecular sieve carbon having such a structure that alarge number of carbon primary particles three-dimensionally irregularlyoverlap and coalesce with each other, in which the average particlediameter of the carbon primary particles is not more than 10 μm whilethe coefficient of variation of the particle size distribution of thecarbon primary particles expressed in the following formula [3] is notmore than 0.65 and a particle bulk density is 0.7 to 1.2 g/cc.

coefficient of variation of particle size distribution of carbon primaryparticles=(standard deviation of carbon primary particlediameters)/(average particle diameter of carbon primary particles)  [3]

Preferably in the molecular sieve carbon according to the presentinvention, the adsorption after 60 seconds from measurement initiationper unit weight of the molecular sieve carbon in single componentadsorption performed with oxygen gas at 25° C. under a pressure of 0.3MPa is 24 to 28 mg/g, and the adsorption after 10 seconds frommeasurement initiation per unit weight of the molecular sieve carbon insingle component adsorption performed with nitrogen gas at 25° C. undera pressure of 0.3 MPa is 0.5 to 5 mg/g. The carbon primary particles arepreferably spherical.

Such a molecular sieve carbon according to the present invention is soused as an adsorbent for a PSA nitrogen generator separating nitrogenfrom mixed gas, such as air, for example, of oxygen and nitrogen thatimprovement in the nitrogen yield per unit weight of the molecular sievecarbon can be attained due to improvement in the nitrogen recoveryresulting from improvement in nitrogen gas purity.

The molecular sieve carbon according to the present invention is nowdescribed in detail. The molecular sieve carbon according to the presentinvention is a pellet-type carbonized article, generally obtained bymolding raw material powder with a binder component or the like andthereafter carbonizing/firing the same, having such an internalstructure that a large number of carbon primary particlesthree-dimensionally irregularly overlap and coalesce with each other.This pellet, not particularly restricted in shape, can be worked into arod shape such as a columnar shape or a granular shape such as aspherical shape, for example. The diameter and the length (height)thereof are preferably set to about 0.5 to 3 mm respectively in the caseof a columnar-shaped pellet, while the diameter thereof is preferablyset to about 0.5 to 3 mm in the case of a granular pellet. The carbonprimary particles denote fine carbon particles forming the pellet-typemolecular sieve carbon obtained by carbonizing phenol resin powder orthe like which is the raw material powder.

The molecular sieve carbon according to the present invention can beused as an adsorbent for a PSA nitrogen generator separating nitrogenfrom mixed gas, such as air, of oxygen and nitrogen, and can also beused for separation of various gas mixtures such as separation ofperfluorocarbon, separation of methane and carbon dioxide andpurification of hydrogen.

The average particle diameter of the carbon primary particles is notmore than 10 μm, and the coefficient of variation of the particle sizedistribution of the carbon primary particles expressed in the aboveformula [3] is not more than 0.65. The coefficient of variation of theparticle size distribution of the carbon primary particles is preferablynot more than 0.6.

The average particle diameter of the carbon primary particles is so setto not more than 10 μm that a molecular sieve carbon having a higheradsorption and a higher adsorption rate of oxygen while having highseparative power for oxygen/nitrogen can be produced. This isconceivably because the yield of pyrolysis gas per primary particle isso reduced in a pore forming step such as carbonization that the numberof fine pores formed on the surfaces of the carbon primary particlesincreases and the diffusion rate of the adsorption gas in the carbonprimary particles quickens due to the small particle diameters.Therefore, when the molecular sieve carbon is employed as the adsorbentfor the PSA nitrogen generator, for example, the nitrogen recovery andthe quantity of the product nitrogen gas per unit weight of themolecular sieve carbon can be improved. The lower limit of the averageparticle diameter, not particularly restricted, is preferably at least0.5 μm, in consideration of productivity in industrial production andsafety. The shape of the carbon primary particles, not particularlyrestricted so far as the same is granular, is preferably spherical, inorder to form more homogeneous pores when the raw material is heated at500 to 1100° C. In the present invention, “spherical” may notnecessarily be truly spherical, but the sectional shape may beelliptical, for example. However, it is advantageous that the shape ofthe raw material is close to a true spherical shape for formation ofhomogeneous pores and for production stability of molding in industrialproduction, and homogeneity in external diffusion of the pyrolysis gasin pore formation in the step of carbonization or the like furtherincreases, and hence the shape of the carbon primary particles is alsopreferably closer to the true spherical shape.

In the present invention, the “average particle diameter of the carbonprimary particles” denotes, in a case of randomly selecting visualfields as to a molecular sieve carbon surface and a rupture phaserespectively in observation through a scanning electron microscope(hereinafter abbreviated as SEM) photograph and arbitrarily selecting100 carbon primary particles confirmable as spherical as to each visualfield, the average of the particle diameters of these 200 carbon primaryparticles measured from the SEM photograph. Further, the “standarddeviation of carbon primary particle diameters” denotes the standarddeviation as to the particle diameters of the aforementioned 200 carbonprimary particles confirmable as spherical.

The molecular sieve carbon according to the present invention,constituted of the carbon primary particles having such a narrowparticle size distribution that the coefficient of variation of theparticle size distribution expressed in the above formula [3] is notmore than 0.65, is superior in separative power for mixed gas of oxygenand nitrogen as compared with a conventional molecular sieve carbon.This is because the particle size distribution of the carbon primaryparticles is so narrowed to reduce the particle diameter differencebetween the respective carbon primary particles that the yield ofpyrolysis gas or the like is rendered constant in the pore forming stepat the time of carbonizing the raw material or the like. Therefore, thepores formed in the carbon primary particles are conceivably homogenizedbetween the respective carbon primary particles. It can also beconsidered as one factor that the depths of the pores included in thecarbon primary particles are homogenized between the respective carbonprimary particles and hence the diffusion rate of the adsorption gas isrendered substantially constant between the respective carbon primaryparticles.

In the molecular sieve carbon according to the present invention, theparticle bulk density is 0.7 to 1.2 g/cc, preferably 0.8 to 1.15 g/cc.The particle bulk density is calculated from the volume and the weightof the pellet-type molecular sieve carbon. The carbon content in themolecular sieve carbon is preferably at least 80 weight %, morepreferably at least 85 weight %.

The molecular sieve carbon according to the present invention has afunction of selectively adsorbing oxygen from source gas mainly composedof oxygen and nitrogen. As to the absorption characteristic thereof, theadsorption after 60 seconds from measurement initiation per unit weightof the molecular sieve carbon in single component adsorption performedwith oxygen gas at 25° C. under a pressure of 0.3 MPa (gauge pressure)is preferably 24 to 28 mg/g. In other words, the molecular sieve carbonaccording to the present invention exhibits a high oxygen adsorption(adsorption rate) in one preferred mode thereof. Further, the adsorptionafter 10 seconds from measurement initiation per unit weight of themolecular sieve carbon in single component adsorption performed withnitrogen gas at 25° C. under a pressure of 0.3 MPa (gauge pressure) ispreferably 0.5 to 5 mg/g, more preferably 1.5 to 5 mg/g. In other words,the molecular sieve carbon according to the present invention exhibits alow nitrogen adsorption rate in one preferred mode thereof. While theseparation accuracy of oxygen/nitrogen separation tends to lower if thenitrogen adsorption in an initial stage (for several seconds, forexample) is large, such reduction of the separation accuracy can besuppressed by reducing the adsorption after 10 seconds from themeasurement initiation. Further preferably, the aforementioned oxygenadsorption after 60 seconds is 24 to 28 mg/g, and the aforementionednitrogen adsorption after 10 seconds is 0.5 to 5 mg/g in the molecularsieve carbon according to the present invention.

The molecular sieve carbon according to the present invention can beobtained by molding raw material powder with a binder component or thelike and thereafter carbonizing/firing the same. While the raw materialpowder is not restricted so far as the average particle diameter and thecoefficient of variation of the particle size distribution of the carbonprimary particles constituting the molecular sieve carbon can satisfythe aforementioned ranges, the aforementioned non-thermofusible phenolresin powder in which the particle diameters and the coefficient ofvariation of the particle size distribution are controlled is preferablyemployed.

When employing a non-thermofusible phenol resin powder as the rawmaterial powder, the boiling methanol solubility thereof is preferablyless than 30%, more preferably less than 20%, further preferably lessthan 10%. While the boiling methanol solubility may be at least 30%, thephenol resin powder may no longer exhibit “non-thermofusibility” in thiscase.

It is also preferable to employ a thermofusible phenol resin powder asthe raw material powder. In this case, the boiling methanol solubilitythereof is preferably less than 50%. The “boiling methanol solubility”can be one index for learning the degree of thermofusibility of thephenol resin powder. In other words, the thermofusibility tends to bereduced as the “boiling methanol solubility” is reduced. While thephenol resin powder may exhibit thermofusibility due to heating orpressurization in use and the particles may be deformed or welded whenthe boiling methanol solubility exceeds 30%, the phenol resin powderexhibits remarkable thermofusibility and there is a possibility thatpores are not sufficiently formed therein due to deformation or weldingof the particles in the carbonization or formed pores are blocked whenthe boiling methanol solubility exceeds 50%. The “boiling methanolsolubility” mentioned here denotes the boiling methanol solubilityexpressed in the above formula [2].

The definition of the “non-thermofusibility” is as described above. The“thermofusibility” means that the phenol resin powder is fused whenabout 5 g of a phenol resin powder sample is inserted between twostainless plates of 0.2 mm in thickness and pressed with a total load of50 kg for two minutes with a pressing machine previously heated to 100°C., and is more specifically defined as such a property that the phenolresin powder forms a flat plate by fusion and/or welding under theaforementioned high-temperature pressurization condition. A phenol resinpowder exhibiting the “thermofusibility” defined as such exhibits athermosetting property at a temperature higher than 100° C., such as atemperature of at least about 120° C., for example. The “thermosettingproperty” means that the phenol resin powder gelates in a gel time testof 180° C.

The average particle diameter of the particles (also referred to asprimary particles as a term with respect to secondary aggregates)constituting the non-thermofusible or thermofusible phenol resin powderis preferably not more than 12 μm. Carbon primary particles having anaverage particle diameter of not more than 10 μm can be formed byemploying a phenol resin powder having an average particle diameter ofnot more than 12 μm as the raw material powder. The definition of the“average particle diameter” of the non-thermofusible and thermofusiblephenol resin powders is identical to the definition of the “averageparticle diameter” of the aforementioned non-thermofusible phenol resinpowder.

Preferably, the non-thermofusible or thermofusible phenol resin powderemployed in the present invention has a narrow particle sizedistribution, and more specifically, the coefficient of variation of theparticle size distribution of the particles (primary particles)constituting the phenol resin powder defined in the above formula [1] isnot more than 0.65. The coefficient of variation of the particle sizedistribution is more preferably not more than 0.6.

The coefficient of variation of the particle size distribution expressedin the above formula [1] is so set to not more than 0.65 that thecoefficient of variation of the particle size distribution of the carbonprimary particles can be set to not more than 0.65, whereby a molecularsieve carbon excellent in separative power for mixed gas can be obtainedas a result. While the coefficient of variation as to the carbon primaryparticles and the coefficient of variation as to the phenol resin powderare different in measurement condition from each other, it has beenconfirmed that, when employing such a phenol resin powder that thecoefficient of variation of the above formula [1] is not more than 0.65,carbon primary particles constituting the obtained molecular sievecarbon satisfy the coefficient of variation of not more than 0.65 of theabove formula [3].

The single particle ratio of the non-thermofusible or thermofusiblephenol resin powder is preferably at least 0.7, more preferably at least0.8. If the single particle ratio is less than 0.7, gas generation bypyrolysis in the carbonization treatment is rendered heterogeneous whilethe shapes and the distribution of the pores formed by the pyrolysis arealso rendered heterogeneous, and the separative power for the mixed gastends to lower as a result. The definitions of the “single particles”and the “single particle ratio” are as described above.

The particle shape of the non-thermofusible or thermofusible phenolresin powder is preferably as close to a spherical shape as possible.More specifically, the sphericity is preferably at least 0.5, morepreferably at least 0.7, particularly preferably at least 0.9. As theparticle shape is closer to a spherical shape, i.e., as the sphericityis closer to 1.0, improvement in the density of a pellet-type molecularsieve carbon obtained by molding a homogeneous mixture with a bindercomponent or the like and carbonizing the same can be attained. Further,the shapes and the distribution of the pores formed by generation ofpyrolysis gas in the carbonization treatment can be rendered morehomogeneous, whereby the separative power for the mixed gas can befurther improved. The definition of the “sphericity” is as describedabove.

Further, the free phenol content in the non-thermofusible orthermofusible phenol resin powder is preferably not more than 1000 ppm.This free phenol content is more preferably not more than 500 ppm,further preferably not more than 400 ppm. Safety in handling of thephenol resin powder can be improved by setting the content of the freephenol which is a harmful component to not more than 1000 ppm. Thedefinition of the “free phenol content” is as described above.

A method for producing a phenol resin powder preferably employed as theraw material for the aforementioned molecular sieve carbon according tothe present invention is now described. A non-thermofusible phenol resinpowder can be suitably produced by the aforementioned method accordingto the present invention. At this time, the loading of the protectivecolloidal agent is preferably at least about 0.05 weight % of theloading of the aforementioned phenolic compound in solid weight. If theloading of the protective colloidal agent is less than about 0.05 weight%, it is insufficient for setting the average particle diameter of thephenol resin powder to not more than 12 μm, and particle size controlwith another parameter such as the loading of the phenolic compound or arate of stirring, for example, is required. The upper limit of theloading of the protective colloidal agent, not particularly restricted,is preferably not more than 3 weight % of the loading of the phenoliccompound. If the upper limit is larger than 3 weight %, the separationrate tends to lower in a separating step described later or the like dueto viscosity increase of the reaction liquid.

A thermofusible phenol resin powder can be obtained by omitting thenon-thermofusibilizing step in the aforementioned method for producing anon-thermofusible phenol resin powder according to the presentinvention. A separating-washing step is similar to that for thenon-thermofusible phenol resin powder.

While the washed non-thermofusible or thermofusible phenol resin powdermay be used as the raw material for the molecular sieve carbon in thehydrous state without being dried, the same is preferably dried.

A method for producing a molecular sieve carbon according to the presentinvention is now described. The method according to the presentinvention is preferably applied for producing the aforementionedmolecular sieve carbon according to the present invention. The methodfor producing a molecular sieve carbon according to the presentinvention includes the following steps:

(i) A step of obtaining a molded substance by molding a homogeneousmixture containing such a phenol resin powder that the average particlediameter is not more than 12 μm and the coefficient of variation of theparticle size distribution is not more than 0.65 and a binder component,and

(ii) a step of obtaining a carbonized molded substance by heating themolded substance under a non-oxidizing atmosphere at a temperature inthe range of 500 to 1100° C.

(i) Molding Step

In this step, a pellet-type molded substance is obtained byhomogeneously mixing such a phenol resin powder that the averageparticle diameter is not more than 12 μm and the coefficient ofvariation of the particle size distribution is not more than 0.65, abinder component and another component, if necessary, with each otherand thereafter molding the mixture. The phenol resin powder is asdescribed above, and more preferably further has a single particle ratioof at least 0.7, sphericity of at least 0.5 and a free phenol content ofnot more than 1000 ppm.

As the binder component, polyvinyl alcohol, a water-soluble orwater-swelling cellulose derivative and coal tars can be listed.Specific examples of the water-soluble or water-swelling cellulosederivative are methyl cellulose, carboxymethyl cellulose andhydroxypropyl methyl cellulose. As the coal tars, coal tar, coal tarpitch, creosote oil and a mixture of at least two types of these can belisted. Thermosetting resin such as phenol resin or melamine resin maybe added as another binder component.

The content of the binder component is preferably about 1 to 50 parts byweight, more preferably 1 to 30 parts by weight with respect to 100parts by weight of the phenol resin powder.

Starch, a derivative thereof or a denatured substance thereof, forexample, can be used as well as the binder component. The component suchas starch suitably acts as a pore forming material, and is pyrolyzed toparticipate in formation of pores in the carbonization under thenon-oxidizing atmosphere. Specific examples of starch etc. are starchsuch as potato starch or cornstarch; a starch derivative such asesterified starch, etherified starch or crosslinked starch; anddenatured starch such as enzyme-denatured dextrine, for example. Thecontent of the starch, the derivative thereof or the denatured substancethereof is preferably about 1 to 50 parts by weight, more preferably 1to 30 parts by weight with respect to 100 parts by weight of the phenolresin powder.

In a range not damaging the characteristics of the molecular sievecarbon, a small quantity of a surface active agent such as ethyleneglycol, polyoxyethylene alkyl ether, polyoxyethylene fatty ester orpolycarboxylate ammonium salt; a hardening agent such as liquefiedthermosetting resin; a crosslinking agent such as polyvinyl alcohol; aplasticizer for extrusion granulation; coconut shell powder; coalpowder; or another synthetic resin, for example, can be added in orderto improve the workability.

A ribbon mixer, a V type mixer, a cone mixer or a kneader, for example,can be employed for the preparation of the homogeneous mixture. Further,a granulation method such as extrusion granulation, rolling granulationor compression granulation can be employed as a method for molding thehomogeneous mixture into the pellet. The pellet-type molded substance,not particularly restricted in shape, can be worked into a rod shapesuch as a columnar shape or a granular shape such as a spherical shape,for example. The diameter and the length (height) thereof are preferablyset to about 0.5 to 3 mm respectively in the case of a columnar-shapedpellet, while the diameter thereof is preferably set to about 0.5 to 3mm in the case of a granular pellet.

(ii) Carbonization Step

In this step, the carbonized molded substance is obtained by heating theaforementioned pellet-type molded substance under the non-oxidizingatmosphere at the temperature in the range of 500 to 1100° C. Thetemperature in the carbonization is preferably 650 to 850° C. There issuch a tendency that only a carbonized substance not having a sufficientadsorption capacity and poor in selective adsorptivity is obtained ifthe carbonization temperature is less than 500° C., while there is sucha tendency that pores of the obtained carbonized substance arecontracted and a sufficient adsorption capacity is hard to obtain if thecarbonization temperature is higher than 1100° C. The heating time canbe set to 1 to 24 hours, for example, and is preferably 1 to 12 hours.Nitrogen or argon can be listed as the gas employed for thenon-oxidizing atmosphere.

While a still standing, fluidized or pivoted heating furnace can beemployed as the heating furnace for the carbonization treatment, apivoted rotary kiln is preferably employed.

After the aforementioned carbonization treatment, a heat treatment maybe performed again at a temperature of not more than 500° C. or at atemperature of not more than 1100° C., in order to adjust thecharacteristics of the molecular sieve carbon. Alternatively, thecharacteristics of the molecular sieve carbon may be adjusted bypulverizing the pellet-type molded substance obtained by theaforementioned carbonization treatment, mixing the same with the bindercomponent or the like again, granulating the same and thereafterperforming a heat treatment again.

The molecular sieve carbon according to the present invention can besuitably employed as an adsorbent for a nitrogen generator. As thenitrogen generator, a nitrogen generator separating nitrogen gas by aPSA system of supplying source gas mainly composed of oxygen andnitrogen, for example, to an adsorption tower filled with the molecularsieve carbon according to the present invention and repeating ahigh-pressure adsorption step and a low-pressure reproduction step inthe adsorption tower can be preferably listed. The molecular sievecarbon according to the present invention is so employed thatimprovement of the quantity of the product nitrogen gas per unit weightof the molecular sieve carbon can be attained due to improvement of thenitrogen recovery resulting from improvement of the nitrogen gas purity,as compared with a conventional nitrogen generator. The nitrogengenerator according to the present invention is now described withreference to a PSA nitrogen generator.

FIG. 14 is a schematic model diagram showing a preferred example of thePSA nitrogen generator according to the present invention. The PSAnitrogen generator shown in FIG. 14 is constituted of two adsorptiontowers 101 a and 101 b filled with the molecular sieve carbon accordingto the present invention; a source gas supply portion constituted of acompressor 102 and an air dryer 103; a product tank 104 storingseparated nitrogen gas; pipes for coupling these components with eachother; electromagnetic valves for controlling the flow of the gas and acontrol system thereof, a flow controller and an analyzer for the gasconcentration.

A driving method for the PSA nitrogen generator shown in FIG. 14 isdescribed. The following driving method is merely an example, and doesnot restrict the present invention at all. First, in the high-pressureadsorption step of adsorption tower 101 a, the source gas compressed bycompressor 102 is dried by air dryer 103, and thereafter supplied toadsorption tower 101 a through electromagnetic valves 105 and 106 a anda pipe 107 a. The source gas, mainly composed of oxygen and nitrogen(air, for example), is pressurized by compressor 102 preferably to about3 to 10 kgf/cm²G.

Oxygen is selectively adsorbed by the molecular sieve carbon inadsorption tower 101 a, and the concentrated nitrogen gas is temporarilystored in product tank 104 through a pipe 108 a, an electromagneticvalve 109 a and a pipe 110, and thereafter extracted as a productthrough a pressure regulator 111 and a pipe 112. After a lapse of aprescribed adsorption time, electromagnetic valves 106 a and 109 a areclosed.

In the low-pressure reproduction step of adsorption tower 101 a, anelectromagnetic valve 113 a is opened for discharging the source gasfilling up adsorption tower 101 a in a pressurized state into theatmosphere through a pipe 114, and the internal pressure of adsorptiontower 101 a is rapidly reduced to a level around the atmosphericpressure, for reproducing the molecular sieve carbon. Further,electromagnetic valves 115 a and 116 are opened for circulating thenitrogen gas in product tank 104 in a counter-flow direction (oppositeto the nitrogen gas extraction direction) toward the adsorption towerthrough a pipe 117, thereby performing reproduction of adsorption tower101 a. Electromagnetic valves 113 a, 115 a and 116 are closed when thisreproduction step terminates, a pressure equalization step is carriedout if necessary, and the high-pressure adsorption step is thereaftercarried out again. As described above, the adsorption step and thereproduction step are so repetitively carried out that reproduction ofthe molecular sieve carbon in the adsorption tower is smoothly performedand high-purity nitrogen gas can be extracted. While the above drivingmethod has been described with reference to the case of using oneadsorption tower, the cycle of the adsorption step—the reproduction stepis alternately performed by employing two adsorption towers when usingthe two adsorption towers.

In the aforementioned driving method, the pressure equalization step anda reflux step may be incorporated to drive the nitrogen generator in acycle of the adsorption step—the pressure equalization step—thereproduction step—the pressure equalization step—the reflux step—theadsorption step, for example. The pressure equalization step is a stepof coupling an adsorption tower terminating the high-pressure adsorptionstep and an adsorption tower terminating the low-pressure reproductionstep with each other and performing pressure equalization of theinternal pressures of the adsorption towers in a case of using at leasttwo adsorption towers. In the case of a nitrogen generator utilizing twoadsorption towers, for example, a case of coupling only upper portionsof the two adsorption towers with each other, a case of coupling onlylower portions with each other and a case of coupling both of the upperportions and the lower portions with each other are referred to as upperpressure equalization, lower pressure equalization and upper/lowerpressure equalization respectively.

The reflux step is a step of simplifying extraction of nitrogen gas of ahigh concentration in the adsorption step by returning a part of thenitrogen gas into the adsorption tower from the product tank and keepingthe nitrogen gas in the adsorption tower without discharging the sameout of the system.

While the present invention is now described in more detail withreference to Examples, the present invention is not restricted to these.

Preparation of Non-Thermofusible Phenol Resin Powder Example 1

A homogeneous solution was obtained by preparing 2000 g of a mixedsolution having a formaldehyde concentration of 10 weight % and ahydrochloric acid concentration of 16 weight % by employing hydrochloricacid of 35 weight % and a formaldehyde aqueous solution of 36 weight %,thereafter adding 8 g of an aqueous solution of 2 weight % ofcarboxymethyl cellulose sodium salt to the mixed solution and stirringthe same. Then, the temperature of the homogeneous solution was adjustedto 20° C., and 70 g of phenol of 95 weight % of 30° C. was thereafteradded while stirring the same. The concentration of the phenoliccompound with respect to the total weight of the reaction liquid is 3.2weight %, the feed molar ratio of the phenol with respect to theformaldehyde is 0.11, and the molar concentration of the hydrochloricacid in the reaction liquid is 4.7 mol/L. The reaction liquid wasclouded in about 120 seconds from the addition of the phenol. When thereaction was continued also after the clouding while reducing the rateof stirring, the reaction liquid was colored pale pink after about 30minutes from the addition of the phenol. At this time, the temperatureof the reaction liquid had reached 30° C. After the coloring of thereaction liquid, the reaction liquid was heated to 80° C. by externalheating, and maintained at this temperature for 30 minutes. Then, thisreaction liquid was filtrated, and the obtained cake was washed with 500g of water, thereafter suspended in 500 g of an ammonia solution of 0.5weight %, and subjected to neutralization reaction at 40° C. for onehour. 80 g of a pale yellow phenol resin powder 1A was obtained bysuction filtration of this suspension with an aspirator after theneutralization reaction, washing the same with 500 g of water and dryingthe same with a dryer of 50° C. for 10 hours.

Example 2

A phenol resin powder 2A was obtained by performing reaction similarlyto Example 1, except that the formaldehyde concentration was set to 18weight % and the hydrochloric acid concentration was set to 18 weight %in the mixed liquid. The concentration of the phenolic compound withrespect to the total weight of the reaction liquid is 3.2 weight %, thefeed molar ratio of the phenol with respect to the formaldehyde is 0.06,and the molar concentration of the hydrochloric acid in the reactionliquid is 5.3 mol/L. The reaction liquid was clouded after about 150seconds from addition of the phenol, and there was no problem inoperation such as adhesion of the resin to a vessel wall or the likeeither. FIG. 2 shows an optical micrograph of the phenol resin powderobtained in this Example.

Example 3

A phenol resin powder 3A was obtained by performing reaction similarlyto Example 1, except that the formaldehyde concentration was set to 7weight % and the hydrochloric acid concentration was set to 20 weight %in the mixed liquid. The concentration of the phenolic compound withrespect to the total weight of the reaction liquid is 3.2 weight %, thefeed molar ratio of the phenol with respect to the formaldehyde is 0.15,and the molar concentration of the hydrochloric acid in the reactionliquid is 5.9 mol/L. The reaction liquid was clouded after about 30seconds from addition of the phenol, and there was no problem inoperation such as adhesion of the resin to a vessel wall or the likeeither. FIG. 3 shows an optical micrograph of the phenol resin powderobtained in this Example.

Example 4

62 g of a phenol resin powder 4A was obtained by performing reactionsimilarly to Example 1, except that 52 g of the phenol of 95 weight %was added. The concentration of the phenolic compound with respect tothe total weight of the reaction liquid is 2.4 weight %, the feed molarratio of the phenol with respect to the formaldehyde is 0.08, and themolar concentration of the hydrochloric acid in the reaction liquid is6.0 mol/L.

Example 5

115 g of a phenol resin powder 5A was obtained by performing reactionsimilarly to Example 1, except that 105 g of the phenol of 95 weight %was added. The concentration of the phenolic compound with respect tothe total weight of the reaction liquid is 4.7 weight %, the feed molarratio of the phenol with respect to the formaldehyde is 0.16, and themolar concentration of the hydrochloric acid in the reaction liquid is5.8 mol/L.

Example 6

A homogeneous solution was obtained by preparing 1156 g of a mixedsolution by mixing 556 g of a formaldehyde aqueous solution of 36 weight%, 70 g of phenol of 95 weight % and 530 g of water with each other,thereafter adding 8 g of an aqueous solution of 2 weight % ofcarboxymethyl cellulose sodium salt to the mixed solution and stirringthe same. Then, the temperature of the homogeneous solution was adjustedto 20° C., and 914 g of hydrochloric acid of 35 weight % of 30° C. wasthereafter added while stirring the same. The concentration of thephenolic compound with respect to the total weight of the reactionliquid is 3.2 weight %, the feed molar ratio of the phenol with respectto the formaldehyde is 0.11, and the molar concentration of thehydrochloric acid in the reaction liquid is 4.7 mol/L, identically toExample 1. The reaction liquid was clouded in about 20 seconds from theaddition of the hydrochloric acid. When the reaction was continued alsoafter the clouding, the reaction liquid was colored pink after about 30minutes from the addition of the hydrochloric acid. Thereafter 78 g of aphenol resin powder 6A was obtained by performing heating, separation,washing and drying similarly to Example 1.

Example 7

240 g of a phenol resin powder 7A was obtained by performing reactionsimilarly to Example 6, except that 204 g of the phenol of 95 weight %was employed. The concentration of the phenolic compound with respect tothe total weight of the reaction liquid is 8.8 weight %, the feed molarratio of the phenol with respect to the formaldehyde is 0.31, and themolar concentration of the hydrochloric acid in the reaction liquid is4.4 mol/L.

Example 8

200 g of a phenol resin powder 8A was obtained by performing reactionsimilarly to Example 6, except that 278 g of a formaldehyde aqueoussolution of 36 weight %, 204 g of phenol of 95 weight % and 803 g ofwater were employed for preparing the mixed liquid. The concentration ofthe phenolic compound with respect to the total weight of the reactionliquid is 8.8 weight %, the feed molar ratio of the phenol with respectto the formaldehyde is 0.62, and the molar concentration of thehydrochloric acid in the reaction liquid is 4.4 mol/L.

Example 9

Reaction was performed similarly to Example 1, except that aparaformaldehyde aqueous solution of the same weight concentration wasemployed in place of employing the formaldehyde aqueous solution of 36weight %. The course of the reaction was substantially identical to thatin Example 1, and 77 g of a phenol resin powder 9A was obtained.

Example 10

A phenol resin powder 10A was obtained by performing reaction similarlyto Example 1, except that the hydrochloric acid concentration in themixed solution was set to 8 weight % and the reaction liquid was heatedto 50° C. by external heating after addition of phenol of 95 weight %and heated to 80° C. after coloring of the reaction liquid. Theconcentration of the phenolic compound with respect to the total weightof the reaction liquid is 3.2 weight %, the feed molar ratio of thephenol with respect to the formaldehyde is 0.11, and the molarconcentration of the hydrochloric acid in the reaction liquid is 2.3mol/L.

Comparative Example 1

80 g of a phenol resin powder 1C was obtained by performing reactionsimilarly to Example 1, except that 8 g of water was employed in placeof 8 g of the aqueous solution of 2 weight % of carboxymethyl cellulosesodium salt. The course of the reaction was similar to that in Example1, except that the reaction liquid was clouded after about 95 secondsafter addition of the phenol. FIG. 4 shows an optical micrograph of thephenol resin powder obtained in this comparative example. As shown inFIG. 4, it is understood that primary particles relatively frequentlyaggregate in the phenol resin powder 1C. The single particle ratio ofthe phenol resin powder 1C is 0.60.

Comparative Example 2

Reaction was performed similarly to Example 1, except that thehydrochloric acid concentration in 2000 g of the mixed solution was setto 5 weight %. No clouding of the reaction liquid was observed, and nophenol resin powder was obtained. The molar concentration of thehydrochloric acid in the reaction liquid is 1.5 mol/L.

Comparative Example 3

Reaction was performed similarly to Example 6, except that 140 g of aformaldehyde aqueous solution of 36 weight %, 204 g of phenol of 95weight % and 940 g of water were employed for preparing the mixedliquid. The concentration of the phenolic compound with respect to thetotal weight of the reaction liquid is 8.8 weight %, the feed molarratio of the phenol with respect to the formaldehyde is 1.23, and themolar concentration of the hydrochloric acid in the reaction liquid is4.5 mol/L. When initiating heating of the reaction liquid, resin adheredto the wall of a reaction vessel. About 50 g of a phenol resin powder 3Cwas obtained by filtrating powder which was in a suspended state uponcompletion of the heating and performing washing, neutralization anddrying. When particles were observed with a microscope, a large numberof indeterminate particles were present, and the sphericity and thesingle particle ratio were impossible to obtain.

Various characteristics shown in Table 1 were measured as to the phenolresin powders 1A to 10A, 1C and 3C. Table 1 shows the results of themeasurement along with reaction conditions.

TABLE 1 Reaction Condition Hydrochloric Phenol Acid Boiling Average FreeCon- P/A *2 Con- Phenol Non- Methanol Particle Single Phenol centration(molar centration *3 Resin Thermofusibility Solubility Diameter ParticleCoefficient Sphe- Content (weight %) ratio) (mol/L) Powder (yes/no)(weight %) (μm) Ratio of Variation ricity (ppm) Example 1 3.2 0.11 4.71A yes 5 5 1.00 0.49 0.99 90 Example 2 3.2 0.06 5.3 2A yes 4 3 0.99 0.380.99 90 Example 3 3.2 0.15 5.9 3A yes 6 7 0.80 0.55 0.90 290 Example 42.4 0.08 4.8 4A yes 3 3 1.00 0.39 0.99 30 Example 5 4.7 0.16 4.6 5A yes7 7 0.80 0.48 0.78 200 Example 6 3.2 0.11 4.7 6A yes 5 2 0.99 0.42 0.9920 Example 7 8.8 0.31 4.4 7A yes 6 2 0.99 0.56 0.99 180 Example 8 8.80.62 4.4 8A yes 8 5 0.80 0.48 0.99 220 Example 9 3.2 0.11 4.7 9A yes 5 50.99 0.57 0.99 100 Example 10 3.2 0.11 2.3 10A  yes 12 12 0.70 0.59 0.88230 Comparative 3.2 0.11 4.7 1C yes 5 17 0.60 0.67 0.80 200 Example 1Comparative 3.2 0.11 1.5 — — — — — — — — Example 2 Comparative 8.8 1.234.5 3C no 40 30 — 0.87 — 1100 Example 3 *1: concentration (weight %) ofphenolic compound with respect to total weight of reaction liquid. *2:feed molar ratio of phenolic compound with respect to aldehyde. *3:molar concentration of hydrochloric acid in reaction liquid.

Example 11

After obtaining phenol resin powders by performing reaction similarly toExample 1 except that the quantity of carboxymethyl cellulose sodiumsalt which is a protective colloidal agent with respect to phenol waschanged in various ways, the average particle diameter of each phenolresin powder was measured. FIG. 5 is a graph showing the relationbetween the concentration of the protective colloidal agent (weight(ppm) of the protective colloidal agent with respect to the total weightof the reaction liquid) and the average particle diameter of the phenolresin powder. The measurement range of 13 to about 103 ppm of theprotective colloidal agent concentration corresponds to the range of0.04 to 0.32 weight % in terms of the ratio (weight %) of the loading ofthe protective colloidal agent/the loading of the phenol. As shown inFIG. 5, it has been recognized that the average particle diameter of theobtained phenol resin powder can be controlled by adjusting the loadingof the protective colloidal agent. In other words, it has beenrecognized that the average particle diameter can be reduced byincreasing the loading of the protective colloidal agent.

Example 12

A homogeneous solution was obtained by preparing 10 kg of a mixedsolution having a formaldehyde concentration of 8 weight % and ahydrochloric acid concentration of 17 weight % by employing hydrochloricacid of 35 weight % and a formaldehyde aqueous solution of 36 weight %,thereafter adding 20 g of an aqueous solution of 2 weight % ofcarboxymethyl cellulose sodium salt to the mixed solution and stirringthe same. Then, the temperature of the homogeneous solution was adjustedto 20° C., and 400 g of phenol of 95 weight % of 40° C. was thereafteradded while stirring the solution. The concentration of the phenoliccompound with respect to the total weight of the reaction liquid is 3.65weight %, the feed molar ratio of the phenol with respect to theformaldehyde is 0.15, and the molar concentration of the hydrochloricacid in the reaction liquid is 5.0 mol/L. The reaction liquid wasclouded in about 70 seconds from the addition of the phenol. When thereaction was continued also after the clouding while reducing the rateof stirring, the reaction liquid was colored pale pink after about 30minutes from the addition of the phenol. At this time, the temperatureof the reaction liquid had reached 30° C. After the coloring of thereaction liquid, the reaction liquid was heated to 80° C. by externalheating, and maintained at this temperature for 30 minutes. Then, about700 g of a wet phenol resin powder 12A-a was obtained by filtrating thisreaction liquid and washing the obtained phenol resin powder cake with 1kg of water. When a part thereof was dried with a dryer of 50° C. for 10hours and thereafter subjected to fluorescent X-ray measurement, thechlorine content in the phenol resin powder was about 6500 ppm. Theaverage particle diameter of the phenol resin powder 12A-a was 3.5

Then, 500 g of the aforementioned wet phenol resin powder 12A-a wasdispersed in 5 L of ion-exchanged water, heated to 95° C. while stirringthe same, and maintained at this temperature for 24 hours. Then, thisdispersion liquid was filtrated, and the phenol resin powder on thefilter paper was washed with 500 g of ion-exchanged water, to obtain aphenol resin powder 12A-b (corresponding to a dry weight of 320 g). Whena part of the obtained phenol resin powder was dried at 105° C. for 10hours and subjected to fluorescent X-ray measurement, the chlorinecontent was 1100 ppm.

Then, the wet phenol resin powder 12A-b (corresponding to a dry weightof 300 g) was dispersed in 900 g of ethylene glycol, heated to 180° C.while stirring the same, and maintained at this temperature for threehours. Then, the dispersion liquid was filtrated after the same wascooled to ordinary temperature, and the phenol resin powder on thefilter paper was washed with 500 g of ion-exchanged water. The obtainedphenol resin powder was dried in a stream of nitrogen at 180° C. forfive hours, to obtain 280 g of a phenol resin powder 12A-c. The chlorinecontent in the phenol resin powder 12A-c was 70 ppm.

Example 13

280 g of a phenol resin powder 13A was obtained similarly to Example 12,except that washing with ethylene glycol was performed twice in total(under the same conditions as Example 12 in both times). The chlorinecontent in the phenol resin powder 13A was 10 ppm. No drying step wasprovided between the first washing and the second washing.

Example 14

A homogeneous solution was obtained by preparing 10 kg of a mixedsolution having a formaldehyde concentration of 8 weight % and ahydrochloric acid concentration of 18 weight % by employing hydrochloricacid of 35 weight % and a formaldehyde aqueous solution of 36 weight %,thereafter adding 30 g of an aqueous solution of 2 weight % ofcarboxymethyl cellulose sodium salt to the mixed solution and stirringthe same. Then, the temperature of this homogeneous solution wasadjusted to 20° C., and 400 g of phenol of 95 weight % of 40° C. wasthereafter added while stirring the same. The concentration of thephenolic compound with respect to the total weight of the reactionliquid is 3.64 weight %, the feed molar ratio of the phenol with respectto the formaldehyde is 0.15, and the molar concentration of thehydrochloric acid in the reaction liquid is 5.3 mol/L. The reactionliquid was clouded in about 60 seconds from the addition of the phenol.When the reaction was continued also after the clouding while reducingthe rate of stirring, the reaction liquid was colored pale pink afterabout 30 minutes from the addition of the phenol. At this time, thetemperature of the reaction liquid had reached 30° C. After the coloringof the reaction liquid, the reaction liquid was heated to 80° C. byexternal heating, and maintained at this temperature for 30 minutes.Then, about 700 g of a wet phenol resin powder 14A-a was obtained byfiltrating this reaction liquid and washing the obtained phenol resinpowder cake with 1 kg of water. When a part thereof was dried with adryer of 50° C. for 10 hours and thereafter subjected to fluorescentX-ray measurement, the chlorine content in the phenol resin powder wasabout 6500 ppm. The average particle diameter of the phenol resin powder14A-a was 5.8 μm.

Then, 500 g of the aforementioned wet phenol resin powder 14A-a wasdispersed in 5 L of ion-exchanged water, heated to 95° C. while stirringthe same, and maintained at this temperature for 24 hours. Then, thisdispersion liquid was filtrated, and the phenol resin powder on thefilter paper was washed with 500 g of ion-exchanged water, to obtain aphenol resin powder 14A-b (corresponding to a dry weight of 320 g). Whena part of the obtained phenol resin powder was dried at 105° C. for 10hours and subjected to fluorescent X-ray measurement, the chlorinecontent was 1700 ppm.

Then, the wet phenol resin powder 14A-b (corresponding to a dry weightof 300 g) was dispersed in 900 g of ethylene glycol, heated to 180° C.while stirring the same, and maintained at this temperature for threehours. Then, the dispersion liquid was filtrated after the same wascooled to ordinary temperature, and the phenol resin powder on thefilter paper was washed with 500 g of ion-exchanged water. The obtainedphenol resin powder was dried in a stream of nitrogen at 180° C. forfive hours, to obtain 280 g of a phenol resin powder 14A-c. The chlorinecontent in the phenol resin powder 14A-c was 90 ppm.

Example 15

280 g of a phenol resin powder 15A was obtained similarly to Example 14,except that washing with ethylene glycol was performed twice in total(under the same conditions as Example 14 in both times). The chlorinecontent in the phenol resin powder 15A was 30 ppm. No drying step wasprovided between the first washing and the second washing.

Example 16

500 g of the phenol resin powder 12A-a obtained in Example 12 wasdispersed in 1.5 L (1350 g) of an ammonia solution of 25 weight %,heated to 37° C. while stirring the same, and maintained at thistemperature for 24 hours. Then, this dispersion liquid was filtrated,and the phenol resin powder on the filter paper was washed with 500 g ofion-exchanged water. The obtained phenol resin powder was dried at 105°C. for 10 hours, to obtain 320 g of a phenol resin powder 16A. Thechlorine content in the phenol resin powder 16A was 300 ppm.

Example 17

320 g of a phenol resin powder 17A was obtained similarly to Example 16,except that washing with the ammonia solution of 25 weight % wasperformed twice in total (under the same conditions as Example 16 inboth times). The chlorine content in the phenol resin powder 17A was 50ppm. No drying step was provided between the first washing and thesecond washing.

Example 18

The wet phenol resin powder 12A-b (corresponding to a dry weight of 300g) obtained in Example 12 was dispersed in 900 g of an ammonia solutionof 25 weight %, and stirred at 80° C. for two hours with an autoclave.Then, this dispersion liquid was filtrated, and the phenol resin powderon the filter paper was washed with 500 g of ion-exchanged water. Theobtained phenol resin powder was dried at 105° C. for 10 hours, toobtain 280 g of a phenol resin powder 18A. The chlorine content in thephenol resin powder 18A was not more than the limit of detection (10ppm).

Example 19

The wet phenol resin powder 12A-a (corresponding to a dry weight of 300g) obtained in Example 12 was dispersed in 900 g of ethylene glycol,heated to 180° C. while stirring the same, and maintained at thistemperature for three hours. Then, the dispersion liquid was filtratedafter the same was cooled to ordinary temperature, and the phenol resinpowder on the filter paper was washed with 500 g of ion-exchanged water.The obtained phenol resin powder was dried in a stream of nitrogen at180° C. for five hours, to obtain 280 g of a phenol resin powder 19A.The chlorine content in the phenol resin powder 19A was 300 ppm.

Example 20

280 g of a phenol resin powder 20A was obtained similarly to Example 19,except that washing with ethylene glycol was performed twice in total(under the same conditions as Example 19 in both times). The chlorinecontent in the phenol resin powder 20A was 60 ppm. No drying step wasprovided between the first washing and the second washing.

Comparative Example 4

100 parts by weight of phenol, 39 parts by weight of paraformaldehyde of92 weight %, 9 parts by weight of hexamethylenetetramine and 1 part byweight of gum arabic were dissolved in 100 parts by weight of water. 7parts by weight of Bellpearl R800 (by Air Water Inc.) was added asnuclear substance, and the mixture was heated to 85° C. in 60 minuteswhile gently stirring the same, and further reacted for 60 minutes whilemaintaining the temperature of 85° C. The obtained reaction liquid wascooled and solid-liquid separated, to obtain a spherical resol resinhaving an average particle diameter of about 500 μm. 100 parts by weightof this spherical resol resin was dispersed in a solution containing1000 parts by weight of hydrochloric acid of 17 weight % andformaldehyde of 9 weight %, heated to 80° C. and maintained for onehour. The reaction liquid was solid-liquid separated by filtration,washed with water, and thereafter dried at 85° C. for five hours. Theobtained resin substantially exhibited non-thermofusibility whilemaintaining the spherical mode and the particle size. The sphericity was1.0, the single particle ratio was 1.0, the average particle diameterwas about 500 μm, the boiling methanol solubility was 6%, and thechlorine content was 4500 ppm. The average particle diameter wasdirectly read from the particle size distribution of an opticalmicroscope image.

These non-thermofusible phenol resin particles having the averageparticle diameter of about 500 μm were subjected to a washing treatmenttwice with ethylene glycol according to the method described in Example13, to obtain a phenol resin powder 4C. The chlorine content in thephenol resin powder 4C was 1200 ppm. No drying step was provided betweenthe first washing and the second washing.

Reference Example 1

500 g of the phenol resin powder 14A-b (chlorine ion content 1700 ppm)obtained in the aforementioned Example 14 was dispersed in 5 L ofion-exchanged water, heated to 95° C. while stirring the same, andmaintained at this temperature for 24 hours. Then, this dispersionliquid was filtrated, and the phenol resin powder on the filter paperwas washed with 500 g of ion-exchanged water. The obtained phenol resinpowder was dried at 105° C. for 10 hours, to obtain a phenol resinpowder 1S. The chlorine content in the phenol resin powder 1S was 700ppm.

Reference Example 2

A phenol resin powder 2S was obtained by performing an operation similarto that in Reference Example 1 as to the phenol resin powder 1S. Thechlorine content in the phenol resin powder 2S was 600 ppm.

Reference Example 3

A phenol resin powder 3S was obtained by performing an operation similarto that in Reference Example 1 as to the phenol resin powder 2S. Thechlorine content in the phenol resin powder 3S was 550 ppm.

Various characteristics shown in Table 2 were measured as to the phenolresin powders 12A to 20A, 4C and 1S to 3S. Table 2 shows the results ofthe measurement along with reaction conditions. Table 2 also showsresults as to the phenol resin powders 1C and 3C.

TABLE 2 Reaction Condition Boiling Phenol Hydrochloric Acid Phenol Non-Methanol Concentration *1 P/A *2 Concentration *3 Resin ThermofusibilitySolubility (weight %) (molar ratio) (mol/L) Powder (yes/no) (weight %)Example 12 3.65 0.15 5.0 12A-a yes 5 12A-b yes 4 12A-c yes 0 Example 133.65 0.15 5.0 13A yes 0 Example 14 3.64 0.15 5.3 14A-a yes 5 14A-b yes 514A-c yes 0 Example 15 3.64 0.15 5.3 15A yes 0 Example 16 3.65 0.15 5.016A yes 4 Example 17 3.65 0.15 5.0 17A yes 4 Example 18 3.65 0.15 5.018A yes 4 Example 19 3.65 0.15 5.0 19A yes 0 Example 20 3.65 0.15 5.020A yes 0 Comparative 3.2 0.11 4.7  1C yes 5 Example 1 Comparative 8.81.23 4.5  3C no 40 Example 3 Comparative — — —  4C yes 6 Example 4Reference 3.65 0.15 5.0  1S yes 4 Example1 Reference 3.65 0.15 5.0  2Syes 3 Example 2 Reference 3.65 0.15 5.0  3S yes 3 Example 3 Average FreeParticle Single Phenol Hydrochlor

Diameter Particle Coefficient Content Acid Conte

(μm) Ratio of Variation Sphericity (ppm) (ppm) Example 12 3.5 1.0 0.450.98 160 about 650

3.5 1.0 0.45 0.98 90 1100 3.5 1.0 0.45 0.98 ND 70 Example 13 3.5 1.00.45 0.98 ND 10 Example 14 5.8 0.9 0.55 0.95 280 about 650

5.8 0.9 0.55 0.95 180 1700 5.8 0.9 0.55 0.95 ND 90 Example 15 5.8 0.90.55 0.95 ND 30 Example 16 3.5 1.0 0.45 0.98 30 300 Example 17 3.5 1.00.45 0.98 ND 50 Example 18 3.5 1.0 0.45 0.98 ND ND Example 19 3.5 1.00.45 0.98 ND 300 Example 20 3.5 1.0 0.45 0.98 ND 60 Comparative 17 0.60.67 0.80 200 about 720

Example 1 Comparative 30 — 0.87 — 1100 about 680

Example 3 Comparative 500 1.0 1.0 1200 Example 4 Reference 5.8 0.9 0.550.95 250 700 Example1 Reference 5.8 0.9 0.55 0.95 200 600 Example 2Reference 5.8 0.9 0.55 0.95 200 550 Example 3 *1: concentration (weight%) of phenolic compound with respect to total weight of reaction liquid.*2: feed molar ratio of phenolic compound with respect to aldehyde. *3:molar concentration of hydrochloric acid in reaction liquid.

indicates data missing or illegible when filed

From each of the aforementioned Examples 12 to 20, it was possible toefficiently obtain a phenol resin powder having a chlorine content ofnot more than 100 ppm by washing with ethylene glycol and/or washingwith an ammonia solution. The alcohol such as ethylene glycol has achemical property easily diffused in the phenol resin particles andimproves the diffusion rate of chlorine ions in the phenol resin, andhence it was conceivably possible to efficiently perform the washing.The washing is conceivably preferably performed in a high-temperatureregion where the motility of the phenol resin molecules increases. Thisalso applies to the case of employing the ammonia solution, such thatthe ammonia solution diffuses into the phenol resin particles therebyimproving the diffusion rate of chlorine ions in the phenol resin andhence it was conceivably possible to efficiently perform the washing.

Observing each of Reference Examples 1 to 3, on the other hand, chlorineions are removed from the surfaces of the phenol resin particles in thefirst washing (phenol resin powder 14A-b: chlorine content 1700 ppm) andthe second washing (phenol resin powder 1S: chlorine content is 700 ppm)with hot water and hence reduction of the chlorine content is observed,while chlorine ions confined in the phenol resin are still present in alarge quantity and spreading diffusion of these internally presentchlorine ions to the surfaces of the particles is rate-determined,whereby the washing effect remarkably lowers in third washing and fourthwashing with hot water as a result. When employing hot water, thechlorine content is not reduced below 500 ppm even if washing isperformed four times, and this operation is extremely inefficient. Asshown in Comparative Example 4, further, it has been recognized that thechlorine content is not sufficiently reduced in a phenol resin having arelatively large average particle diameter, even by washing withalcohol.

FIG. 6 is a scanning electron micrograph (SEM photograph, 500magnifications) of the phenol resin powder 12A-c obtained in Example 12.FIG. 7 is a further enlarged SEM photograph (3500 magnifications) of thephenol resin powder 12A-c. As understood from FIGS. 6 and 7 and Table 2,the average particle diameter, the single particle ratio, the sphericityand the surface states of the phenol resin particles were hardly changedeven by ethylene glycol washing and/or ammonia solution washing, and ithas been confirmed that the washing with ethylene glycol or the ammoniasolution exerts no bad influence on the phenol resin particles.

Preparation of Thermosetting Resin Composition Example 21

Powder which is a thermosetting resin composition was obtained bykneading 6 parts by weight of the phenol resin powder 13A obtained inthe aforementioned Example 13 and 4 parts by weight of epoxy resin(“Epotohto YD-128” by Tohto Kasei Co., Ltd.) on a heated roll whileheating the same to 70° C., thereafter kneading the mixture whilefurther adding 0.2 parts by weight of 2-ethyl-4-methyl imidazole as ahardening agent, removing the kneaded substance from the heated roll andpulverizing the same after cooling. This thermosetting resin compositionexhibited excellent liquidity in melting state, while a gel time at 150°C. was 33 seconds and a gel time at 200° C. was 18 seconds.

Then, this thermosetting resin composition was set in a mold heated to180° C. and maintained with a pressure of 20 kgf/cm² for three minutesto obtain a hardened substance. The obtained hardened substance hadspecific gravity of 1.24, and was lightweight.

Example 22

Powder which is a thermosetting resin composition was obtained bykneading 6 parts by weight of the phenol resin powder 13A obtained inthe aforementioned Example 13 and 4 parts by weight of epoxy resin(“Epotohto YD-8125” by Tohto Kasei Co., Ltd.) on a heated roll whileheating the same to 70° C., thereafter kneading the mixture whilefurther adding 0.2 parts by weight of 2-ethyl-4-methyl imidazole as ahardening agent, removing the kneaded substance from the heated roll andpulverizing the same after cooling. This thermosetting resin compositionexhibited excellent liquidity in melting state, while a gel time at 150°C. was 25 seconds and a gel time at 200° C. was 14 seconds.

Then, this thermosetting resin composition was set in a mold heated to180° C. and maintained with a pressure of 20 kgf/cm² for three minutesto obtain a hardened substance. The obtained hardened substance hadspecific gravity of 1.24, and was lightweight. Further, the obtainedhardened substance had a chlorine content of 70 ppm, and was excellentlyusable as a sealing material for a semiconductor or an adhesive for asemiconductor.

Example 23

A semi-liquefied thermosetting resin composition was obtained bykneading 15 parts by weight of the phenol resin powder 13A obtained inthe aforementioned Example 13, 60 parts by weight of epoxy resin(“Epotohto YD-8125” by Tohto Kasei Co., Ltd.), 6 parts by weight ofphenol novolac resin (TD-2093 by Dainippon Ink and Chemicals, Inc.) and4 parts by weight of dicyandiamide as hardening agents.

Example 24

A thermosetting composition I was obtained by kneading 60 parts byweight of the phenol resin powder 15A obtained in the aforementionedExample 15, 40 parts by weight of epoxy resin (“Epotohto YD-8125” byTohto Kasei Co., Ltd.) and 2 parts by weight of 2-ethyl-4-methylimidazole as a hardening agent. On the other hand, a thermosetting resincomposition II was obtained by kneading 106 parts by weight of fusedsilica (FB-301 by Denki Kagaku Kogyo K.K.) in place of the phenol resinpowder 15A and 2 parts by weight of 2-ethyl-4-methyl imidazole as ahardening agent. The volume ratio of the phenol resin powder 15A in thethermosetting resin composition I and the volume ratio of the fusedsilica in the thermosetting resin composition II are identical to eachother. Then, the thermosetting resin composition I and the thermosettingresin composition II were heated/hardened under a temperature conditionof 150° C. respectively, to obtain hardened substances (referred to ashardened substances Ia and IIa respectively). As to the hardenedsubstances Ia and IIa, torques of the hardened substances at 150° C.were measured with a curast meter VPS by Orientec Co., Ltd.Consequently, the torque of the hardened substance Ia at 150° C. was1.34 times that of the hardened substance IIa. From this, it has beenconfirmed that the hardened substance of the thermosetting resincomposition employing the non-thermofusible phenol resin powderaccording to the present invention was improved in toughness in heating.

Preparation of Carbon Electrode Material Powder Reference Example 4

First, 804 g of the phenol resin powder 1A was obtained by the methoddescribed in Example 1. Then, 680 g of this phenol resin powder wasdivided into four parts, i.e., a phenol resin powder 1A-a (200 g), aphenol resin powder 1A-b (200 g), a phenol resin powder 1A-c (200 g) anda phenol resin powder 1A-d (80 g) and subjected to firing/activationtreatments respectively according to the following conditionsrespectively, to obtain carbon electrode materials 1 to 4 respectively.

(1) Carbon electrode material 1 (yield 94 g): The phenol resin powder1A-a was introduced into a crucible, which in turn was introduced intoan electric furnace. After the electric furnace was sufficientlysubstituted with nitrogen gas, the phenol resin powder 1A-a was heatedfrom room temperature at a rate of 100° C./hour while continuouslyfeeding nitrogen, and heat-treated for three hours when the temperaturereached 600° C. Thereafter the phenol resin powder 1A-a was heated atthe rate of 100° C./hour again, and activated in a stream of nitrogensaturated with steam at 850° C. for five hours. The weight reductionratio indicating the degree of activation was 33%.

(2) Carbon electrode material 2 (yield 60 g): The phenol resin powder1A-b was fired and activated similarly to the phenol resin powder 1A-a,except that the temperature in the activation treatment was set to 900°C. The weight reduction ratio was 56%.

(3) Carbon electrode material 3 (yield 35 g): The phenol resin powder1A-c was fired and activated similarly to the phenol resin powder 1A-a,except that the temperature in the activation treatment was set to 950°C. The weight reduction ratio was 75%.

(4) Carbon electrode material 4 (yield 44 g): The phenol resin powder1A-d was introduced into a crucible, which in turn was introduced intoan electric furnace. After the electric furnace was sufficientlysubstituted with nitrogen gas, the phenol resin powder 1A-d was heatedfrom room temperature at a rate of 100° C./hour while continuouslyfeeding nitrogen, and heat-treated for three hours when the temperaturereached 950° C.

Reference Example 5

200 g of the phenol resin powder 2A obtained by the method described inExample 2 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 90 g of acarbon electrode material 5 having a weight reduction ratio of 36% inthe activation treatment.

Reference Example 6

200 g of the phenol resin powder 3A obtained by the method described inExample 3 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 91 g of acarbon electrode material 6 having a weight reduction ratio of 35% inthe activation treatment.

Reference Example 7

200 g of the phenol resin powder 4A obtained by the method described inExample 4 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 91 g of acarbon electrode material 7 having a weight reduction ratio of 35% inthe activation treatment.

Reference Example 8

200 g of the phenol resin powder 5A obtained by the method described inExample 5 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 92 g of acarbon electrode material 8 having a weight reduction ratio of 34% inthe activation treatment.

Reference Example 9

200 g of the phenol resin powder 6A obtained by the method described inExample 6 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 90 g of acarbon electrode material 9 having a weight reduction ratio of 36% inthe activation treatment. FIG. 9 shows an optical micrograph of thecarbon electrode material powder according to this reference example.

Reference Example 10

200 g of the phenol resin powder 7A obtained by the method described inExample 7 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 92 g of acarbon electrode material 10 having a weight reduction ratio of 34% inthe activation treatment.

Reference Example 11

200 g of the phenol resin powder 8A obtained by the method described inExample 8 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 95 g of acarbon electrode material 11 having a weight reduction ratio of 32% inthe activation treatment. FIG. 10 shows an optical micrograph of thecarbon electrode material powder according to this reference example.

Reference Example 12

200 g of the phenol resin powder 9A obtained by the method described inExample 9 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 90 g of acarbon electrode material 12 having a weight reduction ratio of 36% inthe activation treatment.

Reference Example 13

200 g of the phenol resin powder 10A obtained by the method described inExample 10 was fired and activated under conditions similar to those forthe phenol resin powder 1A-a of Reference Example 4, to obtain 91 g of acarbon electrode material 13 having a weight reduction ratio of 35% inthe activation treatment.

Reference Comparative Example 1

70 g of the phenol resin powder 1C obtained by the method described inComparative Example 1 was fired and activated under conditions similarto those for the phenol resin powder 1A-a of Reference Example 4, toobtain 35 g of a carbon electrode material 14 having a weight reductionratio of 30% in the activation treatment. FIG. 11 shows an opticalmicrograph of the phenol resin powder obtained in this referencecomparative example.

Reference Comparative Example 2

200 g of the phenol resin powder 3C obtained by the method described inComparative Example 3 was fired and activated under conditions similarto those for the phenol resin powder 1A-a of Reference Example 4, toobtain 88 g of a carbon electrode material 15 having a weight reductionratio of 30% in the activation treatment.

Reference Comparative Example 3

Dried coconut shells were introduced into a crucible, which in turn wasintroduced into an electric furnace. After the electric furnace wassufficiently substituted with nitrogen gas, the coconut shells wereheated from room temperature at a rate of 100° C./hour whilecontinuously feeding nitrogen, and heat-treated and fired for threehours when the temperature reached 600° C. Thereafter the coconut shellswere continuously heated at the rate of 100° C./hour, and activated in astream of nitrogen saturated with steam at 850° C. for five hours. Theresultant was pulverized with a dynamic mill [MYD] (by Mitsui MiningCo., Ltd.) until the average particle diameter reached 9 μm, to obtain acarbon electrode material 16.

Reference Comparative Example 4

70 g of the phenol resin powder 1C obtained by the method described inComparative Example 1 was fired under conditions similar to those forthe phenol resin powder 1A-d of Reference Example 4, to obtain 36 g of acarbon electrode material 17.

Various characteristics shown in Table 3 were measured as to theaforementioned carbon electrode materials 1 to 17. Table 3 shows theresults of the measurement. In the carbon electrode material 15 ofReference Comparative Example 2 in Table 3, the single particle ratioand the sphericity are shown by “-”, to indicate that a large number ofindeterminate particles were present and these values were impossible tomeasure.

TABLE 3 Activation or Average Firing Particle Single SpecificTemperature *1 Diameter Particle Coefficient Surface Area (° C.) (μm)Ratio of Variation Sphericity (m²/g) Reference Example 4 CarbonElectrode Material 1 850 4 1.00 0.49 0.99 1105 Carbon Electrode Material2 900 3 1.00 0.47 0.98 1523 Carbon Electrode Material 3 950 3 1.00 0.450.99 2078 Carbon Electrode Material 4 950 3 1.00 0.48 0.99 28 ReferenceExample 5 Carbon Electrode Material 5 850 2 0.99 0.37 0.99 1112Reference Example 6 Carbon Electrode Material 6 850 6 0.80 0.56 0.921105 Reference Example 7 Carbon Electrode Material 7 850 2 1.00 0.360.99 1125 Reference Example 8 Carbon Electrode Material 8 850 6 0.800.47 0.75 1122 Reference Example 9 Carbon Electrode Material 9 850 10.99 0.42 0.99 1065 Reference Example 10 Carbon Electrode Material 10850 1 0.99 0.55 0.99 1096 Reference Example 11 Carbon Electrode Material11 850 4 0.80 0.49 0.99 1099 Reference Example 12 Carbon ElectrodeMaterial 12 850 4 0.99 0.58 0.99 1087 Reference Example 13 CarbonElectrode Material 13 850 9 0.70 0.58 0.85 1109 Reference ComparativeExample 1 Carbon Electrode Material 14 850 15 0.30 0.66 0.40 1111Reference Comparative Example 2 Carbon Electrode Material 15 850 26 —0.86 — 1100 Reference Comparative Example 3 Carbon Electrode Material 16850 9 0.99 0.76 0.45 1123 Reference Comparative Example 4 CarbonElectrode Material 17 950 15 0.30 0.66 0.41 30 *1: firing temperature asto carbon electrode materials 14 and 17, temperature in activationtreatment as to others.

Reference Example 14

After preparing and firing a phenol resin powder similarly to ReferenceExample 4 except that the quantity of carboxymethyl cellulose sodiumsalt which is a protective colloidal agent with respect to phenol waschanged in various ways, an activation treatment was performed at 850°C. for five hours to obtain a carbon electrode material powder, and theaverage particle diameter of the carbon electrode material powder wasmeasured. FIG. 12 is a graph showing the relation between theconcentration of the protective colloidal agent (weight (ppm) of theprotective colloidal agent with respect to the total weight of thereaction liquid) and the average particle diameter of the carbonelectrode material powder. The measurement range of 13 to about 103 ppmof the protective colloidal agent concentration corresponds to the rangeof 0.04 to 0.32 weight % in terms of the ratio (weight %) of the loadingof the protective colloidal agent/the loading of the phenol. As shown inFIG. 12, it has been recognized that the average particle diameter ofthe obtained carbon electrode material powder can be controlled byadjusting the loading of the protective colloidal agent. In other words,it has been recognized that the average particle diameter can be reducedby increasing the loading of the protective colloidal agent.

Application of Carbon Electrode Material Powder to Electric Double LayerCapacitor, Lithium Ion Battery and Lithium Ion Capacitor ReferenceExample 15

A simplified electric double layer capacitor having a structure shown inFIG. 13 was prepared according to the following procedure. FIG. 13 is aschematic sectional view showing the electric double layer capacitorprepared by way of trial. First, a discoidal platinum plate of 1 mm inthickness and 18 mm in outer diameter was employed as a collector 602, adiscoidal silicon rubber member of 0.5 mm in thickness, 3 mm in innerdiameter and 18 mm in outer diameter as a spacer 604 was press-bonded tothis collector 602, and a separately prepared slurried carbon electrodematerial 601 was filled in a hole of 0.5 mm in depth and 3 mm in innerdiameter formed by collector 602 and spacer 604, to form a polarizingelectrode. Two such polarizing electrodes were prepared. Then, adiscoidal polypropylene separator 603 of 25 μm in thickness and 18 mm inouter diameter was held between the two polarizing electrodes, to opposethese two polarizing electrodes to each other. Then, stainless terminalplates 605 for terminal extraction were press-bonded to collectors 602from both sides. The electric double layer capacitor was prepared byapplying a load of 10 kg from above stainless terminal plates 605 forfixation.

The aforementioned slurried carbon electrode material 601 was preparedas follows: After adding the carbon electrode material powder (carbonelectrode material 13, average particle diameter 9 μm) of ReferenceExample 13 and the carbon electrode material powder (carbon electrodematerial 9, average particle diameter 1 μm) of Reference Example 9 intoa vessel in weight ratios shown in Table 4, a sulfuric acid solution of30 weight % which is an electrolyte was added by a constant quantity,and degassing was performed. Then, the sulfuric acid solution of 30weight % was gradually added to this mixed liquid while stirring thesame and the addition was stopped when the mixture in the vessel changedfrom a clayey state to a slurry state, to obtain the slurried carbonelectrode material. Seven types of slurried carbon electrode materials(slurries 1 to 7) in total shown in Table 4 were prepared by thisprocedure. The quantity (g) of the electrolyte used per gram of eachcarbon electrode material is referred to as “electrolyte/electrodematerial ratio”, and shown in Table 4.

Then, the capacitance (F/g) per unit weight of the carbon electrodematerial was measured as to each of the seven types of electric doublelayer capacitors having different types of slurried carbon electrodematerials 601. After applying a voltage of 0.9 V between both electrodesof the electric double layer capacitor and performing constant-voltagecharging for six hours, the electric double layer capacitor wasconstant-current-discharged at 100 μA for obtaining the capacitance (F)of the electric double layer capacitor from the time required forreducing the voltage from 0.54 V to 0.45 V, to calculate the capacitance(F/g) per unit weight of the carbon electrode material from this valueand the weights of the pair of (two) polarizing electrodes. Table 4shows the results.

Further, the coefficient of capacitance per unit volume was obtainedfrom the capacitance (F/g) per unit weight of the carbon electrodematerial, the weight of the employed carbon electrode material and theweight of the added electrolyte according to the following formula.Table 4 shows the results.

coefficient of capacitance per unit volume=(capacitance (F/g) per unitweight of carbon electrode material)×(weight of carbon electrodematerial)/(weight of carbon electrode material+weight of electrolyte)

TABLE 4 Slurry 1 2 3 4 5 6 7 Mixing Ratio *1 30/70 25/75 20/80 15/8510/90 5/95 0/100 Electrolyte/Electrode Material Ratio *2 1.36 1.34 1.301.27 1.31 1.34 1.37 Capacitance (F/g) *3 59 59 59 59 59 59 59Coefficient of Capacitance per Unit Weight of Carbon 25.0 25.2 25.7 26.025.5 25.2 24.9 Electrode Material *1: carbon electrode material 9/carbonelectrode material 13 (weight ratio). *2: quantity of electrolyte usedper gram of carbon electrode material (quantity of electrolyte requiredfor slurrying carbon electrode material of 1 g). *3: capacitance perunit weight of carbon electrode material.

It is understood that the slurry can be prepared with a smaller quantityof the electrolyte by mixing and using the carbon electrode materials 9and 13 according to the present invention prepared by strictlycontrolling the average particle diameters, the particle sizedistributions and the single particle ratios as compared with a singlyusing case, whereby a larger quantity of the carbon electrode materialcan be filled in the electric double layer capacitor and hence thecoefficient of capacitance per unit volume can be further increased. Ithas been recognized that the coefficient of capacitance per unit volumeis most increased in the case (slurry 4) of mixing the carbon electrodematerials 9 and 13 at 15:85 (weight ratio).

When the “electrolyte/electrode material ratio” of the carbon electrodematerial powder (carbon electrode material 16, average particle diameter9 μm) of Reference Comparative Example 3 was measured, a high value of1.49 was exhibited as compared with the value of 1.37 (refer to slurry 7in Table 4) of the carbon electrode material powder (carbon electrodematerial 13, average particle diameter 9 μm) of Reference Example 13.This is presumably because the carbon electrode material powder ofReference Comparative Example 3 has a wide particle size distributionand low sphericity and hence clearances in the carbon electrode materialin the slurry so enlarge that a larger quantity of the electrolyte isrequired for the slurrying.

Reference Example 16

The carbon electrode material powder (carbon electrode material 1,average particle diameter 4 μm) of Reference Example 4 and the carbonelectrode material powder (carbon electrode material 14, averageparticle diameter 15 μm) of Reference Comparative Example 1 wereemployed for preparing electric double layer capacitors as to therespective ones by a procedure similar to that of Reference Example 15,and the capacitances were measured. At this time, the quantities ofdischarge currents were changed from 0.1 mA up to 1.0 mA, for measuringthe capacitances at the respective discharge currents. Table 5 shows theresults.

TABLE 5 Discharge Current (mA) 0.1 0.5 0.8 1.0 Capacitance CarbonElectrode Material 1 61 60 59 58 (F/g) *1 Carbon Electrode Material 1459 46 38 32 * 1: capacitance per unit weight of carbon electrodematerial.

It is understood that reduction of the capacitance is small in theelectric double layer capacitor employing the carbon electrode materialpowder of Reference Example 4 while the capacitance remarkably loweredwith the increase of the discharge current in the electric double layercapacitor employing the carbon electrode material powder of ReferenceComparative Example 1. This is conceivably because the average particlediameter of the electrode material is small as compared with the carbonelectrode material 14 in the case of the carbon electrode material 1 andhence 1) the contact ratio on the interface between the carbon electrodematerial and the electrolyte so increases that adsorption/desorption ofelectrolytic ions with respect to the carbon electrode material bycharging/discharging smoothly progresses, and 2) the diffusion length ofthe ions in the carbon electrode material so shortens thatadsorption/desorption of the electrolytic ions with respect to thecarbon electrode material by charging/discharging smoothly progresses.In other words, desorption of the electrolytic ions quickly respondseven if the discharge current is increased when the average particlediameter of the carbon electrode material is small, while desorption ofthe electrolytic ions cannot quickly respond but the capacitance lowersfollowing increase of the discharge current when the average particlediameter is large.

Reference Example 17

Evaluation of the carbon electrode material powder according to thepresent invention as a negative electrode material for a lithium ionbattery or a lithium ion capacitor was performed in the followingmanner. A slurry was obtained by sufficiently mixing 100 parts by weightof the carbon electrode material powder (carbon electrode material 4,average particle diameter 3 μm) of Reference Example 4 and a solutionprepared by dissolving 10 parts by weight of polyvinylidene fluoridepowder in 80 parts by weight of N-methylpyrrolidone with each other, andthis slurry was applied to a copper foil (20 μm in thickness), dried andpressed to obtain a negative electrode. This negative electrode was cutinto 1.5 cm by 2.0 cm in size, to form a negative electrode forevaluation. A cell for evaluation was assembled by employing thenegative electrode for evaluation, a metal lithium member of 1.5 cm by2.0 cm in size and 200 μm in thickness as a counter electrode and apolyethylene nonwoven fabric of 50 μm in thickness as a separator. Metallithium was employed as a reference electrode. A solution prepared bydissolving LiPF₆ in propylene carbonate in a concentration of 1 mol/Lwas employed as an electrolyte. For the purpose of comparison, a similarcell for evaluation was prepared by employing the carbon electrodematerial powder (carbon electrode material 17, average particle diameter15 μm) of Reference Comparative Example 4.

A charging/discharging test was conducted as to each of theaforementioned cells for evaluation. In an initial charging/dischargingoperation, both of the charging and the discharging were performed at0.2 mA/cm² under potential regulation. The potential range was set to 0V to 2 V on the basis of lithium. Then, second to seventhcharging/discharging operations were performed at 0.2 mA/cm² in thepotential range of 0 V to 0.5 V, and eighth to fifteenthcharging/discharging operations were further performed at 1.0 mA/cm² inthe potential range of 0 V to 0.5 V.

The ratios (capacitance retention ratios, %) between the dischargecapacitances in the seventh operation evaluated at the current densityof 0.2 mA/cm² and the discharge capacitances in the fifteenth operationevaluated at 1.0 mA/cm² were 92% as to the carbon electrode material 4of Reference Example 4 and 69% as to the carbon electrode material 17 ofReference Comparative Example 4. It has been recognized from theseresults that reduction of the discharge capacitance can be suppressed byemploying the carbon electrode material powder according to the presentinvention, even if the current density is increased.

Preparation of Molecular Sieve Carbon Reference Example 18

A homogeneous solution was obtained by preparing 2000 g of a mixedsolution having a formaldehyde concentration of 10 weight % and ahydrochloric acid concentration of 18 weight % by employing hydrochloricacid of 35 weight % and a formaldehyde aqueous solution of 36 weight %,thereafter adding 8 g of an aqueous solution of 2 weight % ofcarboxymethyl cellulose sodium salt to the mixed solution and stirringthe same. Then, the temperature of the homogeneous solution was adjustedto 20° C., and 70 g of phenol of 95 weight % of 30° C. was thereafteradded while stirring the same. The concentration of the phenoliccompound with respect to the total weight of the reaction liquid is 3.2weight %, the feed molar ratio of the phenol with respect to theformaldehyde is 0.11, and the molar concentration of the hydrochloricacid in the reaction liquid is 5.0 mol/L. The reaction liquid wasclouded in about 120 seconds from the addition of the phenol. When thereaction was continued also after the clouding while reducing the rateof stirring, the reaction liquid was colored pale pink after about 30minutes from the addition of the phenol. At this time, the temperatureof the reaction liquid had reached 30° C. After the coloring of thereaction liquid, the reaction liquid was heated to 80° C. by externalheating, and maintained at this temperature for 30 minutes. Then, thisreaction liquid was filtrated, and the obtained cake was washed with 500g of water, thereafter suspended in 500 g of an ammonia solution of 0.5weight % and subjected to neutralization reaction at 40° C. for onehour. 80 g of a pale yellow phenol resin powder 21A was obtained bysuction filtration of this suspension with an aspirator after theneutralization reaction, washing the same with 500 g of water and dryingthe same with a dryer of 50° C. for 10 hours.

Then, 100 parts by weight of the phenol resin powder 21A, 23 parts byweight of coal tar, 5 parts by weight (in terms of solid content) of amelamine resin aqueous solution having a solid concentration of 80weight %, 20 parts by weight of a polyvinyl alcohol aqueous solution(prepared by dissolving polyvinyl alcohol having a degree ofpolymerization of 1700 and a degree of saponification of 99% to providean aqueous solution of 20 weight % with warm water), 24 parts by weightof cornstarch, 9.3 parts by weight of a surface active agent (PellexNB-L by Kao Corporation) and 4 parts by weight of water were measured.

Among the above, those other than the phenol resin powder 21A were mixedfor 10 minutes, and thereafter further mixed for 20 minutes withaddition of the phenol resin powder 21A. This mixed composition wasextruded with a biaxial extrusion granulator (Pelletta Double EXDF-100by Fuji Paudal Co., Ltd.), to obtain a columnar pellet of 1.3 mm indiameter by 1 to 3 mm in length (height). A molecular sieve carbon MSC-1was obtained by heat-treating the obtained pellet in a stream ofnitrogen at 350° C. for four hours, supplying the same to a rotary kilnof 100 mmφ by 1000 mm in usable dimension at 100 g/h, performing acarbonization treatment in a stream of nitrogen of 2 L/min. at aresidence time of six hours and a treating temperature of 750° C. andthereafter cooling the same in the stream of nitrogen. FIG. 15 is an SEMphotograph of the surface of the molecular sieve carbon MSC-1 obtainedin this example.

Reference Example 19

A molecular sieve carbon MSC-2 was obtained similarly to ReferenceExample 18, except that the phenol resin powder 10A obtained in theaforementioned Example 10 was employed.

Reference Example 20

After mixing 100 parts by weight of the phenol resin powder 6A obtainedin the aforementioned Example 6, 10 parts by weight of coal tar, 4 partsby weight (in terms of solid content) of a melamine resin solutionhaving a solid concentration of 80 weight % and 40 parts by weight ofwater, the obtained mixed composition was extruded and granulated into acolumnar shape with a biaxial extrusion granulator (Fine Ryuzer EXR-60by Fuji Paudal Co., Ltd.). Then, a columnar pellet of 1 mm in diameterby 2 to 3 mm in length was obtained from the columnar granule by using amarmelizer (QJ-230 by Fuji Paudal Co., Ltd.). A molecular sieve carbonMSC-3 was obtained by heat-treating the obtained pellet in a stream ofnitrogen at 350° C. for four hours, thereafter introducing the same intoa rotary kiln of 100 mmφ by 1000 mm in usable dimension, heating thesame up to 780° C. in the stream of nitrogen, maintaining the same atthis temperature for three hours and thereafter cooling the same in thestream of nitrogen.

Reference Example 21

A homogeneous solution was obtained by preparing 1156 g of a mixedsolution by mixing 556 g of a formaldehyde aqueous solution of 36 weight%, 70 g of phenol of 95 weight % and 530 g of water with each other,thereafter adding 8 g of an aqueous solution of 2 weight % ofcarboxymethyl cellulose sodium salt to the mixed solution and stirringthe same. Then, the temperature of the homogeneous solution was adjustedto 20° C., and 914 g of hydrochloric acid of 35 weight % of 30° C. wasthereafter added while stirring the same. The concentration of thephenolic compound with respect to the total weight of the reactionliquid is 3.2 weight %, the feed molar ratio of the phenol with respectto the formaldehyde is 0.11, and the molar concentration of thehydrochloric acid in the reaction liquid is 4.7 mol/L. The reactionliquid was clouded in about 20 seconds from the addition of thehydrochloric acid. When the reaction was continued also after theclouding, the reaction liquid was colored pink after about 30 minutesfrom the addition of the hydrochloric acid. At this time, thetemperature of the reaction liquid had reached 30° C. Then, thisreaction liquid was filtrated, and the obtained cake was washed with 500g of water, thereafter suspended in 500 g of an ammonia solution of 0.5weight % and subjected to neutralization reaction at 40° C. for onehour. 75 g of a pale yellow phenol resin powder 5C was obtained bysuction filtration of this suspension with an aspirator after theneutralization reaction, washing the same with 500 g of water and dryingthe same with a dryer of 50° C. for 10 hours.

Then, a molecular sieve carbon MSC-4 was obtained similarly to ReferenceExample 20, except that the phenol resin powder 5C was employed.

Reference Comparative Example 5

100 parts by weight of the phenol resin powder 1C obtained in theaforementioned Comparative Example 1, 8 parts by weight (in terms ofsolid content) of a melamine resin aqueous solution having a solidconcentration of 80 weight %, 20 parts by weight of a polyvinyl alcoholaqueous solution (prepared by dissolving polyvinyl alcohol having adegree of polymerization of 1700 and a degree of saponification of 99%to provide an aqueous solution of 20 weight % with warm water), 2 partsby weight of potato starch and 0.7 parts by weight of a surface activeagent (Pellex NB-L by Kao Corporation) were measured.

Among the above, those other than the phenol resin powder 1C were mixedfor five minutes, and thereafter further mixed for 10 minutes withaddition of the phenol resin powder 1C. This mixed composition wasextruded with a biaxial extrusion granulator (Pelletta Double EXDF-100by Fuji Paudal Co., Ltd.), to obtain a columnar pellet of 1.3 mm indiameter by 1 to 3 mm in length (height). A molecular sieve carbon MSC-5was obtained by treating the obtained pellet by a method similar to thatin Reference Example 18.

Reference Comparative Example 6

A homogeneous solution was obtained by preparing 2000 g of a mixedsolution having a formaldehyde concentration of 10 weight % and ahydrochloric acid concentration of 16 weight % by employing hydrochloricacid of 35 weight % and a formaldehyde aqueous solution of 36 weight %,thereafter adding 8 g of an aqueous solution of 2 weight % ofcarboxymethyl cellulose sodium salt to the mixed solution and stirringthe same. Then, the temperature of the homogeneous solution was adjustedto 20° C., and 70 g of phenol of 95 weight % of 30° C. was thereafteradded while stirring the same. The concentration of the phenoliccompound with respect to the total weight of the reaction liquid is 3.2weight %, the feed molar ratio of the phenol with respect to theformaldehyde is 0.11, and the molar concentration of the hydrochloricacid in the reaction liquid is 4.7 mol/L. The reaction liquid wasclouded in about 120 seconds from the addition of the phenol. When thereaction was continued also after the clouding while reducing the rateof stirring, the reaction liquid was colored pale pink after about 30minutes from the addition of the phenol. At this time, the temperatureof the reaction liquid had reached 30° C. Then, this reaction liquid wasfiltrated, and the obtained cake was washed with 500 g of water,thereafter suspended in 500 g of an ammonia solution of 0.5 weight % andsubjected to neutralization reaction at 40° C. for one hour. 78 g of apale yellow phenol resin powder 6C was obtained by suction filtration ofthis suspension with an aspirator after the neutralization reaction,washing the same with 500 g of water and drying the same with a dryer of50° C. for 10 hours.

Then, a molecular sieve carbon MSC-6 was obtained similarly to ReferenceExample 18, except that the phenol resin powder 6C was employed.

The phenol resin powders employed as raw materials have been collectedin Table 6.

TABLE 6 Reaction Condition Boiling Average Free Phenol Phenol P/A *2Hydrochloric Acid Methanol Particle Single Coefficient Phenol ResinConcentration *1 (molar Concentration *3 Solubility Diameter Particle ofContent Powder (weight %) ratio) (mol/L) Thermofusibility (weight %)(μm) Ratio Variation Sphericity (ppm) 21A  3.2 0.11 5.0 non- 6 6 1.000.49 0.99 70 thermofusible 10A  3.2 0.11 2.3 non- 12 12 0.70 0.59 0.88230 thermofusible 6A 3.2 0.11 4.7 non- 5 2 0.99 0.42 0.99 20thermofusible 5C 3.2 0.11 4.7 thermofusible 47 2 0.99 0.40 0.97 30 1C3.2 0.11 4.7 non- 5 17 0.60 0.67 0.80 200 thermofusible 6C 3.2 0.11 4.7thermofusible 65 5 0.99 0.48 0.96 180 *1: concentration (weight %) ofphenolic compound with respect to total weight of reaction liquid. *2:feed molar ratio of phenolic compound with respect to aldehyde. *3:molar concentration of hydrochloric acid in reaction liquid.

As to the aforementioned molecular sieve carbons MSC-1 to MSC-6, singlecomponent adsorption measurement of oxygen and nitrogen was performedwith an adsorption characteristic measuring apparatus shown in FIG. 16by the following method: Referring to FIG. 16, 30 g of each sample(molecular sieve carbon) was introduced into a sample chamber 312 (250ml), a valve 303 and an electromagnetic valve 305 were closed, a valve302 was opened, degassing was performed with a vacuum pump 301 for 30minutes, and valve 302 was thereafter closed. Then, measurement gas(oxygen gas or nitrogen gas) was fed into a measurement chamber 311 froma gas cylinder 310 in the state closing electromagnetic valve 305, thepressure in the measurement chamber was adjusted to 1.5 MPa (gaugepressure) by controlling a gas regulator 309, and valves 308 and 316were closed. Further, the adsorption of the measurement gas at each timewas obtained by opening electromagnetic valve 305 and measuring aninternal pressure change in measurement chamber 311 at a prescribedtime. The pressure of a constant pressure valve 306 was adjusted to be0.3 MPa (gauge pressure) at this time. While the internal pressures ofmeasurement chamber 311 and sample chamber 312 were measured withpressure sensors 313 and 314, measured values equivalent to valuesdisplayed on a JISB7507 Bourdon tube pressure gauge of an accuracy grade1.6 were employed.

The adsorption Q (mg/g) was calculated through the state equation of gasPV=nRT. P represents the measured pressure (internal pressure ofmeasurement chamber), V represents the spatial volume in the measurementsystem, n represents the number of moles of the measurement gas in themeasurement system, R represents the gas constant, and T represents themeasurement temperature (25° C.). From the pressure difference between apressure P₀ in the initial state of the measurement chamber and apressure P₁ after the adsorption, the difference Δn between a number n₀of moles in the initial stage and a number n₁ of moles after theadsorption was calculated through the following formulas:

n=PV/RT

Δn=(n ₀ −n ₁)=(P ₀ −P ₁)V/RT

Δn corresponds the total of the number of moles of the adsorbedmeasurement gas and the number of moles of the gas introduced into thesample chamber, and hence the adsorption Q per gram of the molecularsieve carbon was obtained through the following formula with the numberΔn₀ of moles of the adsorbed measurement gas obtained by subtracting thenumber of moles of the gas introduced into the sample chamber systemfrom Δn.

Q(mg/g)=1000×Δn ₀(mol)×molecular weight (g/mol) of adsorbed molecules(measurement gas)/weight (g) of molecular sieve carbon

Table 7 shows oxygen adsorptions Q_(O.06s) after 60 seconds from themeasurement initiation and nitrogen adsorptions Q_(N.10s) after 10seconds from the measurement initiation obtained by the aforementionedmeasurement method.

TABLE 7 Reference Reference Reference Reference Reference ReferenceComparative Comparative Example 18 Example 19 Example 20 Example 21Example 5 Example 6 Molecular Sieve MSC-1 MSC-2 MSC-3 MSC-4 MSC-5 MSC-6Carbon Oxygen Adsorption 25.8 24.7 27.8 24.3 22.8 20.5 Q_(O,60s)(mg/g)Nitrogen Adsorption 4.4 2.0 3.3 3.0 2.7 2.0 Q_(N,10s)(mg/g)

The aforementioned molecular sieve carbons MSC-1 to MSC-6 were filled inadsorption towers 101 a and 101 b of the PSA nitrogen generator shown inFIG. 14, and nitrogen generability was evaluated. All of the weights ofthe filled molecular sieve carbons were rendered identical to eachother.

First, air compressed with compressor 102 was fed to adsorption towers101 a and 101 b, the pressures of the adsorption towers were set to 9.5kgf/cm²G in gauge pressure, and a PSA operation was executed in foursteps of upper/lower pressure equalization-adsorption-upper/lowerpressure equalization-reproduction (purge). The steps were switched bycontrolling the electromagnetic valves with a sequencer. The extractionflow rate (quantity of product nitrogen gas) of product nitrogen wasstandardized to 2.5 NI/min. per kilogram of each used molecular sievecarbon, and the oxygen concentration of the obtained product nitrogenwas measured with an oxygen densitometer and subjected to evaluation.The adsorption time and the pressure equalization time were optimized.Table 8 shows the oxygen concentration (ppm) in each product nitrogen.Table 8 also shows the average particle diameter, the coefficient ofvariation of the particle size distribution and the particle bulkdensity of each molecular sieve carbon. As to the molecular sieve carbonMSC-6, carbon primary particles were welded to each other, and theaverage particle diameter and the coefficient of variation wereimpossible to measure.

TABLE 8 Reference Reference Reference Reference Reference ReferenceComparative Comparative Example 18 Example 19 Example 20 Example 21Example 5 Example 6 Molecular Sieve MSC-1 MSC-2 MSC-3 MSC-4 MSC-5 MSC-6Carbon Average Particle 4.2 9.8 1.4 1.4 15 — Diameter (μm) Coefficientof 0.2 0.6 0.1 0.1 0.7 — Variation of Particle Size DistributionParticle Bulk Density 1.1 1.0 0.92 0.82 1.0 1.1 (g/cc) OxygenConcentration 25 60 10 55 100 800 (ppm)

It is understood that the oxygen concentration in the product nitrogencan be remarkably reduced by employing the molecular sieve carbons(MSC-1 to MSC-4) according to the present invention. In the PSA nitrogengenerator, it is generally known that the purity of nitrogen lowers ifthe quantity of product nitrogen gas is increased while the purity ofnitrogen increases if the quantity of the product nitrogen gas isreduced in a case of employing the same molecular sieve carbon (forexample, Reference Document 1: “Pressure Swing Adsorption TechniqueCompilation” edited by Toshinaga Kawai, Kogyo Gijutsukai, issued onJanuary, 1986). FIG. 17 is a diagram showing the relation between thepurity of product nitrogen and the flow rate of product nitrogen gas ina PSA nitrogen generator employing molecular sieve carbons havingdifferent nitrogen recovery (i.e., the difference in separative powerfor oxygen/nitrogen, the nitrogen recovery is expressed as nitrogenrecovery=(quantity of product nitrogen gas/quantity of nitrogen gas insupplied source gas) in a nitrogen generator filled with a molecularsieve carbon). Thus, when a molecular sieve carbon exhibiting a highnitrogen recovery is employed, the purity of the product nitrogen can beincreased at the same flow rate of the nitrogen gas. In other words,this relation means that, in a case of employing a molecular sievecarbon capable of generating product nitrogen of higher purity at thesame quantity of product nitrogen gas, the quantity of the productnitrogen can be further increased under a condition of the same purityof the product nitrogen.

Therefore, the quantity of the product nitrogen gas can be furtherincreased as compared with the prior art by employing the molecularsieve carbon according to the present invention, whereby the quantity ofthe product nitrogen gas per unit weight of the molecular sieve carboncan be remarkably improved due to improvement of the nitrogen recovery.

Measurement methods and measurement conditions for variouscharacteristics as to the phenol resin powder, the carbon electrodematerial powder and the molecular sieve carbon are as follows:

(1) Non-Thermofusibility and Thermofusibility: When inserting about 5 gof a phenol resin powder sample between two stainless plates of 0.2 mmin thickness and pressing the same with a pressing machine previouslyheated to 100° C. with a total load of 50 kg for two minutes, a casewhere the phenol resin powder did not form a flat plate, the phenolresin particles were not deformed, or the phenol resin particles werenot bonded to each other by fusion and/or welding was determined ashaving “non-thermofusibility”. When the phenol resin powder formed aflat plate by fusion and/or welding under this high-temperaturepressurization condition, the phenol resin powder was determined ashaving “thermofusibility”.

(2) Boiling Methanol Solubility: About 10 g of a phenol resin powdersample is precisely weighed, heated in about 500 mL of substantiallyanhydrous methanol under reflux for 30 minutes, thereafter filtratedthrough a glass filter of No. 3, and the residue on the glass filter iswashed with about 100 mL of anhydrous methanol. Then, the washed residueon the glass filter is dried at 40° C. for five hours, and this residueis thereafter precisely weighed. From the weight of the dried residue asobtained and the weight of the phenol resin powder sample, the boilingmethanol solubility is calculated on the basis of the following formula:

boiling methanol solubility (weight %)=(difference between weight ofphenol resin powder sample and weight of dried residue)/(weight ofphenol resin powder sample)×100

(3) Average Particle Diameter: A value of a cumulative frequency of 50%in a frequency distribution measured with a laser diffraction particlesize measuring apparatus (Microtrac X100 by Nikkiso Co., Ltd.) whilepreparing a water dispersion liquid with the carbon electrode materialor the phenol resin powder.

(4) Single Particle Ratio: A ratio in a case of dispersing the carbonelectrode material or the phenol resin powder in water droplets, makingobservation with an optical microscope and counting the total number ofprimary particles and the number of single particles in a randomlyselected visual field containing about 300 primary particles, i.e., thenumber of single particles/the total number of primary particles.

(5) Coefficient of Variation of Particle Size Distribution: Calculatedaccording to the following formula [1] from the frequency distributionmeasured with the laser diffraction particle size measuring apparatus(Microtrac X100 by Nikkiso Co., Ltd.) while preparing the waterdispersion liquid with the carbon electrode material or the phenol resinpowder:

coefficient of variation of particle size distribution=(d _(84%) −d_(16%))/(2×average particle diameter)  [1]

In the above formula [1], d_(84%) and d_(16%) represent particle sizesexhibiting cumulative frequencies of 84% and 16% in the obtainedfrequency distribution respectively. The carbon electrode material orthe phenol resin powder was determined as having a narrow particle sizedistribution when the coefficient of variation was not more than 0.65.

(6) Sphericity: In a case of randomly deciding a visual field containingabout 300 primary particles in observation with an optical microscope,selecting 10 primary particles having the lowest aspect ratios (i.e.,ratios of minor axes/major axes) and measuring aspect ratios inprojected profiles thereof as to the respective ones of these 10 primaryparticles, the average of these 10 aspect ratios.

(7) Free Phenol Content: Defined as a value calculated by the followingtest: In other words, about 10 g of a phenol resin powder sample isprecisely weighed, extracted in 190 mL of methanol under reflux for 30minutes, and filtrated through a glass filter. The phenolic compoundconcentration in the filtrate is determined by liquid chromatography,and the weight of the phenolic compound in the filtrate is calculated.The ratio between this weight of the phenolic compound and the weight ofthe sample, i.e., the weight of the phenolic compound/the weight of thephenol resin powder sample is regarded as the “free phenol content”.

(8) Chlorine Content: After a pellet for measurement is prepared bypressurizing a measurement sample (non-thermofusible phenol resinparticles) and binder powder for measurement, fluorescent X-ray analysisis performed in an EZ scan mode with a fluorescent X-ray analyzerZSX100E by Rigaku Corporation. A diffraction strength measured value ofa chlorine Kα ray is standardized from an estimated molecular formula(C₇H₆O₁) of a phenol resin hardened substance, and regarded as thechlorine content (wt/wt).

(9) Specific Surface Area: Obtained according to the B.E.T. method bynitrogen adsorption by correctly weighing about 0.1 g of the carbonelectrode material and thereafter introducing the same into a dedicatedcell of a precision full-automatic gas adsorption apparatus BELSORP-miniII (by Bel Japan, Inc.).

(10) Average Particle Diameter of Carbon Primary Particles constitutingMolecular Sieve Carbon: In a case of randomly selecting visual fields asto a molecular sieve carbon surface and a rupture phase respectively inobservation through a scanning electron micrograph and arbitrarilyselecting 100 carbon primary particles confirmable as spherical as toeach visual field, the average of the particle diameters of these 200carbon primary particles measured from the SEM photograph. Further, the“standard deviation of carbon primary particle diameters” denotes thestandard deviation as to the particle diameters of the aforementioned200 carbon primary particles confirmable as spherical.

(11) Coefficient of Variation of Particle Size Distribution of CarbonPrimary Particles constituting Molecular Sieve Carbon: Obtainedaccording to the following formula:

coefficient of variation of particle size distribution of carbon primaryparticles=(standard deviation of carbon primary particlediameters)/(average particle diameter of carbon primary particles)

The embodiment and Examples disclosed this time are to be considered asillustrative in all points and not restrictive. The range of the presentinvention is shown not by the above description but by the scope ofclaims for patent, and it is intended that all modifications within themeaning and range equivalent to the scope of claims for patent areincluded.

1-14. (canceled)
 15. A nitrogen generator employing pellet-typemolecular sieve carbon as an adsorbent for air separation, having such astructure that a large number of carbon primary particlesthree-dimensionally irregularly overlap and coalesce with each other,wherein the average particle diameter of said carbon primary particlesis not more than 10 μm, the coefficient of variation of the particlesize distribution of said carbon primary particles expressed in thefollowing formula [1] is not more than 0.65 and a particle bulk densityis 0.7 to 1.2 g/cc; and wherein formula [1] is: coefficient of variationof particle size distribution of carbon primary particles=(standarddeviation of carbon primary particle diameters)/(average particlediameter of carbon primary particles).
 16. The nitrogen generatoraccording to claim 15, wherein the adsorption after 60 seconds frommeasurement initiation per unit weight of the molecular sieve carbon insingle component adsorption performed with oxygen gas at 25° C. under apressure of 0.3 MPa is 24 to 28 mg/g, and the adsorption after 10seconds from measurement initiation per unit weight of the molecularsieve carbon in single component adsorption performed with nitrogen gasat 25° C. under a pressure of 0.3 MPa is 0.5 to 5 mg/g.
 17. The nitrogengenerator according to claim 15, wherein said carbon primary particlesare spherical.